Issuu

S Association magazine of W.S.G. Abacus

Divisibility Titbits

Werner Scheinhardt A Day With...

The Candidate Board The First

Pranab "Praat"

\begin{Summer} 2020

INDEX 4 5 9, 10, 11 15 18

Columns Staff Says General Adjunct's Thoughts Your Story The Pen Pranab "Praat" Mathematical How tuning an instrument becomes 22 a very irrational task

6 11, 14 12 19 20 21 21 23 24

Fun A Day With... Puzzles Interview Puzzle Solution Mathematical Memes Poetry Where are the Abacus members going this summer? On the Couch Review: S.V.K.B. Primo Ballerino

Editorial Dear reader, Times surely are changing quickly, aren’t they? Are the restaurants open yet? Is the new normal still one, like probability taught us? On the scale from 1 to 10 it might not even be that far off for a lot of people. But I’m sure you all are getting kind of done with Covid-19, lightly speaking. So let’s play a little game, to lighten up the mood. First answer these 3 questions: What is the current colour of your underwear? What is the last thing you’ve eaten? Why does the universe exist, if not existing is actually an equally valid option? Easy questions of course, but we're trying to lighten up the mood here. Now fill them into the story below: There once was a guy named Mike. Mike was the adventurous type, always hiking and mountain climbing. After many years of training, he would finally attempt to climb the Mount Everest. He would do this with his close childhood friend, Baltasar. Baltasar was also very adventurous, and you could see it at first sight. He always wore his glitter backpack, orange cap and neon pink hiking shoes. He even painted his hair (fill in first answer)!

this tale be an ordinary one. After days of climbing they sat under the stars and ate their dinner. Baltasar ate a can of soup and Mike ate (Fill in second answer). Baltasar said to Mike: ”Are you really going to eat that? That is absolute trash”. But after it was roasted for a quick moment, it was half decent. The next day they continued climbing. It had been absolutely exhausting. So this is what happened: Mike lost focus, and from one moment to another he was hanging on the edge of the mountain only holding on to the arms of his partner. Baltasar started to doubt the mental state of his friend and asked: ”Why does the universe exist?”. Confused he quickly answered, still fearing for his life: (fill in third answer). Baltasar, calm as could be, asked: ”Are you not going to ask me what I think the answer would be?” To which he said aggravatedly : ”Well Baltasar, why do you think the universe exists?” To which he answered: ”Yo mama!”, and dropped the Mike.

AGENDA • 10 July Deadline Photobook • 19 August Beginning Kick-In • 24 August Pubquiz Twick-In • 25 August Games night Twick-In • 25 August Live Interview: Candidate Board

Stay safe, Timon Veurink

They were standing at the foot of Mount Everest. The smell of pine trees filled them with determination. Under no circumstances would

Colophon Editorial address: W.S.G. Abacus Postbus 217, 7500 AE Enschede Phone: 053 - 489 3435 ideaal@abacus.utwente.nl www.abacus.utwente.nl Editors: Emma Donkers Jorg Gortemaker Yanna Kraakman Lavinia Lanting Carmen Tretmans Timon Veurink

Guest writers: Werner Scheinhardt (Staff Says), Tugce Akkaya (General Adjunct's thoughts), Pascal Loonhuis (Your Story), Martijn Heutink (Your Story), Jorn de Jong (Your Story), Martijn ter Steege (Sudoku with a twist), Pranab Mandal (Pranab "Praat"), Daan Pluister (Geoguessr Sudoku), Lars van de Velde (Poetry), Imre van Veldhoven (S.V.K.B. Primo Balerino)

Ideaal! is the magazine issue of Wiskundig Studiegenootschap Abacus and the department of Applied Mathematics. The responsibility for the articles published in this magazine lies with the original author(s). The period of notice of Abacus is four weeks before the end of the association year (August 1st). That means that you must cancel your membership before July 4th. If you have forgotten to cancel your membership before that time, you will pay contribution for another college year. Would you like to cancel your membership? Send an email to board@abacus.utwente.nl.

Staff Says Text: Werner Scheinhardt Divisibility titbits First of all, I hope that you (math students and staff) are healthy and that you are feeling well despite the strange and sometimes difficult circumstances in which we all need to study and work these days. I considered writing something related to this whole Covid-19 situation1, but decided against it and wrote about a more pleasant subject: something more 'recreational', related to my presentation for the Applied Math Education Prize earlier this year. This talk2 covered three examples of how convenient math notation can make a big difference, and that conventional notation is not always the most convenient. Those of you who were present probably remember the last example, a case for using τ = 6.28318530... as the circle constant, rather than π = 3.14159265.... But now I would like to say a bit more about the first example in the talk, on the so-called 'Arabic' numeral system (which as I mentioned is not really Arabic since it originated in India). Over the course of many years this system replaced the conventional 'Roman' numeral system (which was not really Roman since the Greeks, Hebrews and others used similar systems) due to its advantages: it is a positional system, in which each integer number x ∈ ℕ is uniquely represented by a sequence of symbols (digits), the values of which depend on the position in the sequence. Thus, e.g. 355 = 3·102 + 5· 101 + 5·100, and for general x,

In the slides there is an example of the extreme usefulness of this representation, e.g. when determining the product of two integers (involving a double summation and a carrying procedure to ensure digits never become larger than 9). 1

Here we will look at the following problem: how to quickly recognize whether or not some large integer x is divisible by i? Algorithms to do so are often of the form: x is divisible by i if and only if fi(x) is divisible by i where fi(x) is typically a (much) smaller integer than x, so that we can either immediately check divisibility, or apply the same algorithm again (iteratively if needed). Well-known are: f2(x)= f5(x) = f10(x) = x mod 10 = x0 f4(x)= x mod 100 = x0+10x1 f8(x)= x mod 1000= x0+10x1+ 100x2 The proofs for these cases are based on the fact that 10 is divisible by 2, 5 and 10, that 100 is divisible by 4, and that 1000 is divisible by 8. Consider for instance i = 4, then:

So both x and f4(x) are divisible by 4, or both are not. The cases i = 3 and i = 9 are based on the sum of the digits:

9, or both are not. But also, both x and f9(x) are divisible by 3, or both are not. A similar result is possible for i = 11, where we take an 'alternating sum' of the digits, i.e. we can take The proof is also similar:

Divisibility by i = 6 (or i = 12) is of course decided by checking both i = 3 and i = 2 (or i = 4), so we now covered all cases i = 1,...,12, except the nasty prime i = 7. A quick search3 shows the following, which is completely not obvious at first sight - at least not to me: a number x is divisible by 7 if and only if the number, after removing the last digit and then subtracting that last digit twice, is divisible by 7. In other words we can use:

The proof is slightly dierent since the result of the algorithm, unlike the cases above, is not necessarily the remainder after division (i.e., x mod 7 = f7(x) mod 7 need not hold):

The proof relies on Newtons binomium:

So both x and f9(x) are divisible by

So both x and 10·f7(x) are divisible by 7, or both are not. But since 10 and 7 are relative prime, the same statement holds when we replace 10·f7(x) by f7(x). Notice that we can also check divisibility in another, more convenient base than 10; divisibility by 7 for instance is easy to check in the octal system (with base 8) by considering the sum of the 'digits'. E.g., the number 2020 is given in base 8 as 3744, which has 22 (= 2 · 8+2)

Spread of viruses can be modeled by Markov chains; second year students will see this in module 8. 2 For those who missed the talk, you can find the slides on my home page under 'teaching', see https://www.utwente.nl/en/eemcs/sor/sta/scheinhardt/

see e.g. https://www.aaamath.com/div66 x7.htm

for its sum of 'digits', which has 4 for its sum, which is not divisible by 7 (and indeed, expressed in the decimal system 2020 divided by 7 has remainder 4). Before finishing, let me mention that the number 360 obviously meets all tests above for i = 2,...,10 except for i = 7 (in fact 360 is the smallest number with this property). There are 360 degrees in a circle, but there were also 360 days in the year according to many ancient civilizations. Thus the year could be divided without remainder in many ways, but interestingly the number of days in a week was determined

at exactly . . . 7. Hence, the day of the week could not be determined by the date in the year. Finally, sticking to the counting of time: I hope you will all be healthy and successful for the rest of this academic year, and that you will have a healthy and refreshing summer holiday after that, for at least 10! seconds (which is exactly 6 weeks).

General Adjunct’s Thoughts Text: Tugce Akkaya The Quarantine Diaries - This Too, Shall Pass I woke up to the sound of the birds chirping on a beautiful sunny morning… The temperature of my bedroom is getting warmer, I want to put one of my feet outside of my blanket…Am I in a tropical hotel room? Oh no wrong alarm! My cat Mia realized I woke up, she jumps on my bed and is checking me whether or not I am fully awake. There is no point in pretending to sleep… I jump out of bed…and step on a plug! But in my mind! I felt exactly like that by remembering the idea of being in quarantine due to the Corona virus… I immediately forgot how beautiful the morning was. I would like to read all news before I wash my face… Every morning, I realize I started to give less emotional reaction to the news like other people around me. I do not want to share anymore what I read in the news with my family/friends WhatsApp groups. I also started to receive less #quarantinechallenge invitations. I already watched all episodes of La Casa de Papel, I tried new recipes (I am still proud

of myself for my home-made Turkish pizza, aka ‘Lahmacun’), I made a book list which I was planning to read before, I cleaned my wardrobe and reorganized my bookshelf/ drawers… I am grieving the loss of my old routine and trying to adapt myself the so-called ‘het nieuwe normaal’. I must be close to the last stage ‘acceptance’ in KüblerRoss Grief Cycle, wherein the five stages are: denial, anger, bargaining, depression, and acceptance… Nowadays I tend to reading positive news and articles! I would like to share with you a Persian folktale… Once upon a time there was a king who desired a ring be made for him. The ring was to be a special one: it was to carry an inscription such that if the king was sad, he could look at the ring and it would make him happy, and if he was happy,…it would make him sad…. Many men and women came forward with suggestions for the ring, but the king liked none of them. Then the king’s great advisor found a dervish and asked for help. A few days later, an emerald ring was made and presented to the king. The king, who had been depressed for days, reluctantly put the ring on his finger… Then he started to smile, and a few moments later, he was laughing

loudly. On the ring were inscribed the words, “This too shall pass.” We all try to deal with this crisis in our own way. I like to think that this too shall pass. It won’t always be this way. But truth is, with all the grief the world has experienced, it's hard to imagine we'll be the same again.

A Day With...

We had the pleasure to talk to Daan Velthuis, Luuk van der Werf, Daan Pluister, Jorn de Jong and Anouk Beursgens, the five student members of the 53rd Candidate Board of W.S.G. Abacus

Text: Jorg Gortemaker and Lavinia Lanting

Shortly present yourself and your future role. V: I am Daan Velthuis, but, since we have another Daan in the candidate board, you can call me Velthuis. I am the candidate Chairman, I am 19, I live in Glanerbrug, but I come from Enshede. L: Yo fakka! Hello readers. Fakka readers. I am Luuk. I turned 20 during this fabulous corona time and I am the candidate Secretary and also the candidate Officer Internal Affairs. I come from the beautiful Kampen, but I was born in Zwolle, which is a bit of a pity to be honest. P: I am Daan Pluister, candidate Treasurer for the 53rd board of W.S.G. Abacus. I come from Heerhugowaard. That is situated on the other side of the Netherlands and I wanted to study in Enschede because it’s quiet here and there is a lot of nature. I always love to play games. I’ll give the word to Jorn. J: If you have read the previous Ideaal!, you must have read this already in “On the couch”, where I had to introduce myself. I am Jorn de Jong and I am the candidate Officer External Affairs. Like the majority of the candidate board, I too am 19 years old. A: I am Anouk Beursgens and I am the candidate Officer Educational Affairs. I too am 19 and I come

from Maarssen nearby Utrecht. J: Pluister forgot to say that he is also candidate Officier Cookies. P: That I am! I forgot to mention it. A: I am also the candidate Officer Books Sales. L: I don’t make the minutes. Disclaimer: Lavinia makes those.

Were these the tasks and roles you were hoping to be nominated for when you signed up? Why? V: I hesitated between Chairman and Officer External Affairs, but I eventually chose Chairman due to how these roles suited me within committees. L: I have also been Extern for committees, but I didn’t enjoy it that much… :P I applied for Intern. I didn’t apply for Secretary, but I wanted two functions and it needs to be done. I will learn something from this too. P: I applied for Treasurer, the most fun function: giving out money. Doing stuff in Excel is also fun. J: I had given the position of Treasurer my preference and Extern was the second in line. Once we got to know what our roles would be I started thinking about it and realised that this too is a lot of fun. A: My preference went to Educational Affairs. It seemed interesting to me to represent students and

you learn a lot about the educational system and what needs to change. I think it’s a nice reason to be able to speak to members.

Who of you has the most important task and why? P: Book Sales! V: The most important task is not one of our functions, but the task that we as board carry out together for the association. L: Disgusting. P: This is what we tell others, but it’s actually the Officer Book Sales who does everything.

How does it feel to be the first online candidate board Abacus has ever had? A,L: It sucks. V: I think a nice alternative has been found for the current situation. A: I agree with Velthuis, but it’s a pity and it could have been so much more fun. P: I learnt how to wash my hands. A: I now know how to use lots of online platforms. V: I think that the importance of real-life meetings can now clearly be seen. As it turns out, you can’t replace contact.

What’s your typical day like as a candidate board? L: Look at Instagram, yeah! Let’s go! And by the way, Kampen is definitely more beautiful. Enschede is a shitty city. The university is amazing, but the city isn’t. V: I have online meetings. For the rest I actually don’t do that much. A: We have a lot of coffee dates with other candidate boards and we also need to study.

the entire day visiting companies. I can just talk to them online. P: For me it’s more difficult, because Sanne has a lot less to do right now, so she needs to invent things so that she can teach me. L: It’s fine for me. Martijn shares his screen and plans some activities and makes minutes. A: Sometimes it’s difficult to follow the training, but yeah...we can’t all sit in the Abacus room while learning.

Do you feel that you are missing out on anything of your candidate board experience due to the current situation?

We already know that your motto will be “Fakka fakka”, but have you already chosen the colour of your board?

V: Especially the contact we have with other candidate boards is a lot more difficult and less spontaneous. A: The coffee dates are indeed a bit less fun than expected and all the small talk runs out after a while. L: You miss drinking a lot and also your candidate round. I also miss the Vesting Bar and the Abscint.

A: No, veto! L: Anouk, don’t lie. P: You can’t know that. V: Top secret! L: Classified. V: How did you even find out about that motto? Jorn I am looking at you. You can’t see it on this screen, but I am looking at you. P: I also think Jorn leaked this info. J: What are we talking about? According to me we don’t have a motto yet.

What is the thing you are most looking forward to as a candidate board? L: Things offline. Fun things in real life. Being able to hold again all the activities that there exist. A: Yes, things offline. J: Going again to Texel on the Active Members Weekend. L: Cobo in real life. I am looking forward to that. V: Constitution Drink! I don’t want this board to say cobo. By the way, I am looking forward to getting to know the other candidate boards. L: I am looking forward to not being approved as board.

How much harder or easier has it become to learn about your tasks? V: No clue. I think it’s going well now. J: It costs me in any case a lot less time, since I don’t have to spend

L: I am second in constitutional order, so I claim it. A: I think the Vice should get it. L: But Anouk is too nice. I just want to let an entire crate be chugged on the Active Members Weekend at 8 in the morning.

Luuk, you will be Officer of Internal Affairs. Do you think you can ever match Martijn’s enthusiasm when promoting activities? At least how many people can we expect you to bring to each activity? L: I thought the question would be about Martijn’s alcoholism. Martijn is definitely a very cheerful guy, but I will do my very best. I will always be there in any case, so I will definitely bring at least one person. For the rest I don’t really know with online and such.

Pluister, you will be Treasurer. How do you intend to protect Abacus’ money? P: Well, I heard that Sanne wants to put all the money on reserve, so I can’t even spend it.

Velthuis, you will be Chairman. How do you intend to keep the rest of your board members in line?

Jorn, you will be Officer of External Affairs. Which of the current Abacus’ partners is your favourite and why?

L: He won’t! HAHAHA! V: If I look at my fellow board members, I think that everything will be fine. And I will take action when needed. L: That’s what you think. P: Again such a politically correct answer. Just tie us to a pole or something. V: If you don’t do your action points on time, anytimer it is. That will be the policy. L: Or they need to buy a ‘frikandelbroodje’, right? But who would own the anytimer? V: The Chairman, of course. L: But what if you don’t do your action points on time? V: Then the Vice-Chairman will have an anytime on me.

J: Well, they are all special in their own way. I don’t have a favourite. You also can’t choose between your two children and in the same way you can’t choose between different partners. The ones that are most useful for the members I also like as an answer. L: But which are those? J: Well, that depends on each member.

Anouk, you will be Officer of Educational Affairs. How many extra resits can students expect to obtain with your help? A: Well, I assume just one. I would say, just study well for your exams and then you’ll be fine.

J: You should have said hopefully zero. L: That the lectures will be so good that you won’t even need a resit. Luuk, you will also be Secretary. Do you believe that the rest of the candidate board will have anything useful to say for you to take minutes of? L: Certainly not, no no no. I discovered that not too long ago.

What new Abacus merch can we expect to be able to buy once you are board? A: A sports bottle! I want a sports bottle. P: I want mouse mats. That’s why I became part of the board. A: Inter-Actief has toiletry bags. We could have an Abacus toothbrush. V: Reusable shopping bags of Abacus or Abacus flip flops. A: Flip flops are a great idea! L: Yellow underpants. Or maybe a sweater without a hoodie or just a t-shirt. V: Abacus letter opener. P: Is this all being annotated? Abacus clothespins. V: Abacus Nintendo DS. L: Abacus towel. V: This merch sells itself.

What will you change about the Abacus room once you can enter it again? V: We really want that people can sit there again. L: I don’t even know what it looks like anymore. I haven’t been there in so long. A: A new lemonade can would be nice.

Pluister, how does it feel to be candidate board together with the kiddos of your yearmates? And are you sad none of your own kiddos became candidate board? P: I think they are very nice people, so I like that I have my nephews

here with me. I think it’s a pity though that my adopted kiddo didn’t become a board member. Lavinia: Sorry, Daan. Maybe next year. P: We’ll keep you to this. Lavinia: I’ll do it next year. Then I will be following your steps. P: Very good. V: I also want this to be in the interview. P: Or you might want to keep this a secret. You can also do that. L: But by whom do you want to be trained? You will be Secretary, right? Lavinia: Yes, of course. L: Nice! But then maybe you will teach me rather than I teach you.

V: Well, I have the CoCo and EWI Trip, but I heard that the CoCo always needs help, so I’m looking the most forward to that. P: Ideaal! of course. J: WWW. It’s handy, since I will then immediately know if we broke the website, but I am also looking forward to RSA and Symposium. A: I am looking forward to multiple things. The Sport Day committee because you can wear out everyone and such and I am curious what the Gala committee will be like as a board member.

Which committee(s) will you be doing next year?

P: I don’t have to miss anything. L: Pixcie, clearly A: I agree with that. L: That is also the only one I will stop doing. V: Well, the WWW I will continue doing and EWI Trip also still exists, sort of, so I also don’t have to miss anything. J: The Auditing committee I will definitely miss.

L: None. V: Yes, we won’t do any committees. P: Oh, I will. J: I will as well. V: Oh wait, I also still am in the WWW. I will stay in there. P: Nice Daan. Nice Velthuis. L: Who is Daan? P: But everyone stays in a committee, because you will stay in the Twick-In, since camp will be held later on. A: Oh yeah. V: Well, we hope so. P: I will just stay in the RSA committee. L: But who will become a bartender and who will become a ERO is not a secret, right? A: Well, we can probably only get our ERO diploma after 3 months, so it will still take a while before we can join the (h)ERO committee. V: We all did a bartending course. L: It was useful. V: I had one wrong answer. L: I had 2. J: Amateurs.

Following which committee are you most looking forward to? L: Pixcie ‘vo.

Which committee that you are currently in will you miss the most next year?

What are your hopes for Abacus for the coming year? J: Our dream is to make a super good puzzle for the Active Members Weekend. L: My dream is going to Texel for the Active Members Weekend. P: But we are going there anyways, so that’s easy. L: Oh yeah. A: I would like more to be done with regards to mental and social health, but that was a very serious answer with respect to the rest. V: My hope is that we can fulfill the dreams of all of our members this year. P: And that everyone will love one another. Oh and no corona, of course.

Any last words you would like to share? L: 53 ‘vo.

P: Well, I would like to say fakka fakka, but I know that doesn’t apply to everyone. L: Fakka fakka I can definitely agree with. Fakka fakka. P: Not, not everyone agrees with it, so we can’t say that. L: Anouk, say it. You know you want it. A: No. V: I’ll just say ‘vo 53. L: Two words. Say it and I’m yours: fakka fakka. V: This will be a great year. I want to say that. A: I would like to point out that Velthuis was truly politically correct during this entire interview. V: Nobody had expected that. J: Thanks for the interview. L: Ideaal! ‘vo. A bit less than

53 though. And Kampen ‘vo, of course, but that before Ideaal!.

Your Story Text: Pascal Loonhuis When I heard that the lockdown was actually going to take place, I thought I would definitely bore myself to death. Especially when my roommates told me they would leave the house to go to their parents for an indefinite amount of time. This meant that after one week of lockdown I was all alone in my house in Enschede and that I needed to talk to the walls in order to start a conversation. During the weekdays it was surprisingly easy. I had to concentrate myself on the master thesis so time went by very fast. During the first few weeks I only saw myself in the mirror, my bed, bathroom, dishwasher, microwave, bike, Albert Heijn, one friend in Enschede and my parents during the weekend. Later on I began to see some friends from my parents’ hometown during the weekends. Looking back on this period, I have to say that everything went smoothly. Seeing only a handful of people

without further obligations was quite relaxing actually. Of course, this situation is not ideal. Many opportunities for joy, like drinking beer with other students, were taken away. Besides that I had some nice activities planned with friends and family but, of course, they didn’t take place. I have to admit that the only 2 things I really missed were the weekdays at the university and the gym. Other than that I was fine. The upside to this story is the fact that I saved a lot of money haha. That’s good news I guess!

I will succeed this year. If I don’t succeed to reach that level, I still hope to reach at least the tan level of Cas Sitvast. Please pray for me! I hope that you and your family stay healthy!

During these days I still can meet friends and family so I cannot complain. It’s way worse for people who own businesses and need to feed their family. Feeding myself is not so difficult since my former colleagues from South Korea sent me 2 huge boxes of good quality Korean ramen haha. With the good weather coming up, I have time to enjoy some time outside and work on getting a nice tan. That project didn’t succeed since 2006. Due to working in a factory during the summer break I never reached the tan of Enrique Iglesias. I hope

Your Story Text: Martijn Heutink What it is like to teach Mathematics As of this moment i don’t think that anyone will deny that we are in a very turbulent time. Most of our everyday businesses are changed or are not allowed. This is for everyone and everything including schools, which all had to close. All lessons have been moved to online environments and with that a lot of new challenges appeared. I will tell a little bit of my experiences as an intern in a high school during this period and the challenges we face. We shall start at the beginning. I started my internship at the end of january as of this year. This internship is taking place in Raalte. Here I have responsibility for two entire classes without interference from anyone. The classes are a vwo 5 and a havo 4 class both doing mathematics A. What I enjoy most about these classes is that every lesson is different. One day the lesson is going very well and everything happens the way you planned it, while the next day the lesson is absolute garbage and it doesn’t have to be your fault. The challenge of teaching is not the mathematics itself, but how do you teach someone else something that is completely obvious to you and how do you keep your class under control. Think of things like differentiating, how do you explain that to someone who has never seen it, or how do you keep the attention of the entire class? These are a couple examples with which you have to deal in a lesson. For people who think this is easy, I would like to invite them to try and see for themselves. I know of an example and ask of you how to deal with the situation. The situation is as follows. The bell has just rung and a new class is coming into the

room. One of the boys carries with him a ladder and when you inquire on how he got it, he tells you that he found it on his way to the lesson and brought it along. How do you deal with the situation? This example is not from my own experience but it did happen. Although teaching can be difficult and exhausting it is also very rewarding. Students have the ability to surprise you with new knowledge, gestures and insights, which makes teaching really diverse and very fun to do. Before I start with telling how I teach nowadays, I will firstly tell what a “normal” lesson would look like. I purposely quote “normal” because there are a lot of ways to teach and all of them have their pros and cons. Also currently the definition of a “normal” lesson is quite different due to circumstances. The most important part is that a “normal” lesson for you should be fitting for your style of teaching and can be completely different from what I would do. For me a lesson already starts before the students enter the room. I like to make a list with bullet points as to what we are going to do today. After this I will stand at the door and greet the students as they enter the room. This way I have time for a little bit of small talk and already assess and influence the students a little bit. I want to know what is going on, because if they had gym and I want to start with an explanation of 20 minutes then that is doomed to fail. When everyone is sitting down, have their books and I have their attention, then I start. How I start explaining, depends on the topic. This can be an entire topic on it’s own, but I will leave that for another time. I usually take 10 to 15 minutes for my explanation. Any longer than this and the attention of your students is probably gone. After this I let them work on their own for about 10 minutes. I usually reserve 5 minutes to handle an exercise or a small bit of theory. After this I will

let them work on their own again. A couple minutes before the hour is up, I will end the lesson with the students together. This is for me a standard lesson, but this doesn’t mean I won’t deviate from it. This was just a small impression of how it is to teach a class in “normal” circumstances. At this moment the situation is obviously completely different. All of the lessons have been moved to online environments. This transition is a bit weird and brings a lot of new challenges. Nowadays it is a lot easier to keep the class under control, students are muted and they cannot spam in the chat. This however means that the interactions with the students is limited, which I think is unfortunate. Most of your interactions with students in a class are the small interactions, not the ones where you ask them how to solve an exercise. With the students muted it has become difficult to have these small interactions, you cannot ask one student how their weekend was because the entire class is waiting and listening in on the conversation. Another difficulty of teaching online is that you cannot control what the students do during your lesson. They can be on their phone, they can play games and you won’t see it. The same holds for exams, how do you make sure they don’t cheat? For some of these things you just have to accept that you can’t do anything about it, but not all of them. You can test at the beginning or during your lesson if your students can react to something and if they don’t or do it slow you know that they weren’t paying attention. We as teachers have to be creative in our methods to reach the students. You might have noticed it yourself or at least it holds for me, I find it hard to motivate myself when I am home the entire day and the students experience that the same. At this moment I give to every class one lesson a week where all students have to be present. In this

hour I discuss a difficult paragraph and after that I speak to every student individually on how they are doing. Beside this I make a video of every paragraph that the students can watch. These are about ten minutes in which I explain that section. This is my way of trying to reach the students, keep them interested and try to teach them new mathematics. They have one mandatory hour with me and they have a schedule for the entire week and they can decide when they do what. This obviously depends on the cooperation of the students and their own responsibility.

I was a bit cynical at first about this, but the students have positively surprised me with their efforts and the method is quite a success. As we can see, there are challenges, but it is not all bad.

Your Story Text: Jorn de Jong I was asked to write a story about how I am experiencing the current situation. Well, that sounded hard, because I did not do much worth sharing during this period. But boy, that changed, that changed a lot. Take a seat because this will probably be the best story you ever read. It all started on the 15th of April, me and my apartment mates found a nice house that was available for rent. Fast forward two days, and we went to view this house. Well, it was beautiful, there was even a garden and a basement. We were sold. Fast forward another three days, and we got the renting contract. Wooh, party. However, there is one small problem, the basement is probably going to flood every winter.

Since fixing this is way too expensive, we only have one other option: Placing a lot of beer crates on the floor so we do not stand in the water. The only problem with that is that we need a lot of beer creates (and as far as I am aware, you cannot just go to a store and buy crates without beer). That is not a problem, you would say. Since the crates have to be upside down, they must be empty. And there is the problem that all those bottles have to go back to the store, but not in a crate. The only good way to do this of course is just to go the supermarket with bags filled with empty bottles. However, this again created a new problem. Apparently, the Lidl bottle return machine could not handle that much empty bottles without crates and it broke down. Since we are very helpful guys, we offered to place all our bottles in a crate and hand those in instead of only bottles. Since the box fillers

were not that smart, we just got free crates to hand in. That is basically the end of this amazing story. We got some free money from the Lidl. It was fun. Will definitely try again.

Puzzle: <310JQK Text: Timon Veurink MA1408195726021961SE0803184408071859TO0504191816121965JO1108195207021999 NO2109195717011991GB2201190106051910SW0209196821091982MA2602196123071999 SE1809187208121907GB06021952

Interview

This time we interviewed Linda ten Klooster, Martijn ter Steege, Sanne Oude Veldhuis and Marjolein Bolten for the last time in their role of 52nd Board of W.S.G. Abacus before leaving the stage.

Text: Carmen Tretmans and Lavinia Lanting

What did you want to become when you were kids? MtS: Board. L: A dolphin trainer. S: I don’t know. M I think I can answer for Sanne: Soccer Player. S: No, I did not. Mj: For me it's Physiotherapist. MtS: I wanted to be a soccer player. A professional one. And I am. S: I really don’t know. I think maybe an astronaut. It’s the only thing I can imagine but I don’t really remember.

Has your board year given you more perspective on ‘working life’? L: No. Mj: just about sitting the whole day in an office. But apart from that not really. L: I don’t think there is a drink almost every day in working life. S: But sitting behind your computer at a desk is similar. L : That’s true. S: So possibly yes. MtS: I looked into some companies that looked interesting.

Who is the best chess player? L, Mj: Martijn! MtS: There is no competition here.

L: But who would be the worst? MtS: Linda or Marjolein. Mj: Linda! MtS: Maybe you should challenge each other. L: I don’t even remember all the rules. S: Yes, Linda is the worst. MtS: Who is the worst would have been a better question.

Has Martijn managed to become the manliest board member? All: uhhmmm… S: Maybe…? L: He is still trying. MtS: I’m doing some push ups during corona time. L: So corona helps you become a man? S: Send a picture of your abs as proof! MtS: No! S: Then you’re not manly. Martijn leaves the Discord S: Walking away from your problems is very manly.

Your board year is not quite finished. Anything you’re still looking forward to? L : To this evening: the Candi announcement drink. S: Teaching the Candis everything. MtS: The Candi round. Oh wait...

L: Nevermind. Mj: To everything that is now cancelled. MtS: Oh wait.. L: Before corona I was really looking forward to the end of the year activity.

What was the thing you were most looking forward to that got cancelled due to Corona? L, Mj, S: Active Members Weekend. MtS: Candi round.

Would you consider doing an extra board year (due to Corona)? Mj: Not for Abacus. If, then for something different. And just because I’d like to do another board year. S: Haven't you heard yet? We are announcing ourselves tonight L: I would need more reasons to do another board year, not just corona. We are still a board. S: I don't think I will do another board year.

Where was the Active Member Weekend supposed to take place? All: Texel!! L: We can't say it yet, even though it will not take place.

S: Maybe the next board could use our location.

What was the nicest moment during the board year? Mj: I think the DRAMA. It was one of the last things that took place and it was really nice. But that is also because there are no activities anymore. S: The Lustrum. L: The Constitution Drink. All: Yeah, definitely. MtS: Maybe the Kick-In. L: Also the camp. It was so much fun!

Which one was the nicest activity? L: I really liked the christmas dinner. S: For me it is the old boards’ day. L: That was fun too. MtS: The end-of-the-semester drink. Mj; I still think the DRAMA was nice. MtS: You’re such a drama queen! L: It was actually the nicest bartending I ever did.

Was it easier than expected to be board? MtS: We didn't expect corona. Mj: It wasn't easier. L: I agree, it was not easier. Harder is a strange word but it was very different than expected. S: Some tasks were harder, some were easier. L: The GMA’s were easier. Mj: Some small stuff was harder than I thought. MtS: Especially more time consuming. Fixing small things takes a lot of time and effort.

How much harder (or easier) has your job become since the beginning of the quarantine? S: Way easier! L: Way harder! My task is to keep everyone connected and that is way harder.

S: I think it is function specific. There is not a lot happening in finances. L: For me it is way harder to do what I am supposed to do. M : I think for me as well. Minute making is harder online. Organising activities is way harder. However, you don't get distracted anymore, you work more efficiently and that works very well. Mj: For me it is easier. Contact with companies was already via mail or phone, that didn't change. Visiting companies is easier since I don't have to travel by train anymore.

What does it feel like being the first online board of Abacus? Mj: Not really different. MtS: It is unique. I think a lot of people understand our situation, that we are trying to make something out of it. But we have to do it with all the members of Abacus. If I may quote a High School Musical song: We ‘re all in this together! L: I really hope this is not happening again. I hope for the next board they do not have to do everything online.

What are your hopes for the next 10 years for Abacus? S: No corona! MtS: Wat Sanne said. S: And no other pandemic. Mj: That when we can meet in person again it's just the same as before and that there are no other problems. S: That it is even better than before and we can enjoy each other's company even more. L: Yes, appreciate the company. And that the abacus room will be cooler.

What is your plan for next year? Mj: Doing a minor in Amsterdam. L, S: That sucks! L: Visiting Marjolein in Amsterdam. L: Sanne and I will do a minor

Leren Lesgeven. MtS: I hope to graduate. L: Yes, that too.

What are you looking forward to in the coming year? S: The first activity or drink that will take place. L: Yeah, especially the ones we didn't do this year, like the Active members weekend. MtS: To the summer BBQ! L: With cold weizen. S: No, with cold apple juice!

Any tips for the candidate board? S: Just go with the flow! MtS: Have a corona back up plan. L: Stay positive. Mj: Enjoy your time. L: Even if things don't go like you would like them to. MtS: Just enjoy. Thumbs up, mmm. L: Like and subscribe?

Which committee was the most fun to help out? L: I really liked helping the Christmas Dinner committee. S: The old boards’ day. Mj: Prom. MtS: The Twick in 2019. I didn’t have to do anything. S: I liked all PixCie meetings. Mj: Didn't you like the EEMCS trip meetings? S: Yes, I like all meetings. MtS: I liked the Lustrum committee. Especially promoting because the members were all older years, so they weren’t promoting to younger years. That was my job.

Are you joining any (new) committees next year? Mj: Maybe, I don't know yet. MtS: The Amsterdam committee? Or the external committee, for all people outside of Enschede? L: I probably want to join the Symposium committee. S: I will join the auditing committee.

L: You kind of have to, donâ€™t you? S: I donâ€™t have to but I would like to. Aside from that I don't know yet. I will see next year.

wants to be like us. Mj: I don't support this message.

What is your greatest achievement this year?

Continue with the time and stay safe!

Any last words?

L: uuhhm... S: Difficult question. L: Including the employees into the association. For example at the sinterklaasdrink, there were a lot of employees. I was really proud about that. MtS: I agree. Mj: Everything we did on social media is also really nice. S: The Active Members Weekend. Mj: Yeah, indeed. L: Finding a candidate board. MtS: No that's not fun. S: The question was about your greatest achievement. MtS: That was not an achievement either. We are so fun, everyone

Puzzle: Sudoku with a twist Suggested by: Martijn ter Steege In this sudoku, you can see the first few digits of pi. To solve it, the normal sudoku rules apply. Additionally, a digit can not be placed if the same digit is within a chess king's move. Good luck!

The Pen Text: Lavinia Lanting Murder, She Wrote As some of you may know, in the early days of May this year I organised the so called Red Thread Game: a week during which participants would receive a puzzle each day. In exchange for the correct solution, they would obtain a piece of a murder story, which, at the end of the week, they had to solve to let justice triumph. What many may not know is that the idea for the Red Thread Game was born thanks to my own fascination with the world of detective stories. It is no secret that I adore reading about the adventures of Sir Arthur Conan Doyle’s beloved detective Sherlock Holmes and his most trusted right-hand Doctor John H. Watson. So much so that I jumped at the opportunity of being able to experience one last mystery along their side by reading “The House of Silk” by Anthony Horowitz and ended up in tears reading the epilogue, in which an old and tired Watson dearly remembers his now dead companion and acknowledges his own time being near when he hears the sound of the violin Sherlock used to play and thinks to himself that he would love for them to meet again. That single epilogue perfectly shows exactly why I love those characters so much: their humanity and the artistry of the writer in bringing them to live in a way that I, the reader, can see and feel everything they do is something that from a young age only ever grew my fascination with this world. It is for example by reading Agatha Christie’s “Murder on the Orient Express” that I first truly started realising that justice is never truly a black or white matter: in that single moment when Hercule Poirot renounces all of his rules and lies about what truly happened, I grew alongside him in my understanding of what the meaning of the word ‘just’ is.

Another, in my opinion, intriguing aspect about some of these characters is their relationships. I for example firmly believe that Lieutenant Columbo’s wife is the most interesting character of the series. While the viewers never once get to see even a glimpse of her, they get to know her better each episode as Columbo narrates just one more anecdote involving her to explain to the culprit how he solved the case. This kind of dynamic is also what makes Midsomer Murders quite unique, as Joyce Barnaby or the daughter Cully somehow always manage to hint Detective Chief Inspector Tom Barnaby in the right direction only by casually conversating with him. The thing is, this fascination of mine with the world of detective detective stories goes far beyond what you might think, to the point where it influenced some of my dreams for the future. While I was still being indecisive about whether I wanted to study medicine or mathematics, I knew one thing for sure: had I chosen medicine, I would have studied to become a coroner and there was no changing my mind. While I don’t expect you to know many who would ever want to become a coroner, I personally felt like that was the perfect way of combining my passion for biology and chemistry with my shyness and my interest in the detective world. In a way, I suppose I just wanted to be like Kathleen Joan Toelle Reichs, a forensic anthropologist whose knowledge and experience inspired her own series of books, on which the series “Bones” is loosely based. I wanted, like her, to be able to utilise my knowledge to crown the one true dream that I’ve had since I first picked a book as a child: to be a writer, in this case a detective stories’ writer.

it is most certainly no mere chance that in my first year I immediately joined the Ideaal! Committee. For months on end now I’ve been writing my own short novel, unfortunately only ever managing to write very little each time, as most of my time was spent constructing my main characters, the world they act in and researching various topics like poisonous substances and how the human body changes after so many hours after the death. The last few months though, thanks to the quarantine, weirdly enough, I’ve been able to find a lot of time to do my research, speeding up the process quite a bit. My hope remains that some day I’ll finally be able to finish writing my novel and that I’ll manage to give my readers the feeling of being capable of walking right next to my main characters, the feeling of standing right there as they unveil the mystery, just as I am there every single time in the room where Poirot or Ellery Queen reunite all suspects and characters of the stories to explain and solve the mystery piece by piece.

My love for mathematics and the atmosphere in Enschede and at Abacus eventually won my heart over and the rest is history, but my will to become a writer never died and

Just Abacus things...

Pranab "Praat" Text: Pranab Mandal Krrring, Krrring! - Hallo, Pranab Mandal here … - Oh, hi! I was actually expecting your call … - Yes, yes. I know. You will be coming in a mont-… - Sorry? You want to come now? But I thought … - Ok, that will be fine … - So, you mean like playing hideand-seek: you will count to 20, and then come look for me… - Ok, let me put you on speaker phone, while I get ready: “one, two; Here I come, ready or not!” - WHA-?! The fictive telephone conversation above just about sums up how the arrival of the programme directorship felt to me. I am sure many of you have the same feeling about being abruptly thrown into the uncertainty of COVID-19. The fact is that, this is probably not the last time that we face such impromptu tests in our life. We better learn as much as we can during the journey through now and prepare ourselves for any unknowns in the future. The same holds, by the way, about the exams. As teachers, we face so often questions like how many questions there will be, or if this particular theorem will be asked in the exam. In my opinion, considering that “learning” is the main goal of education, we all should try to learn (or teach) the given topics as best as we can and prepare for any eventuality. Coming back to my current situation, I must admit that I have been lucky to be surrounded not only by great colleagues and dedicated teachers, but also by the cooperative students of our programme. Thanks to their continuous support and the ever extended helping hand of Abacus, the transition to online teaching went without major hiccups. In any case, while I was slowly getting used to the new work (and the style thereof) under lockdown

or quarantine, I heard people talking about WFH. Not being very savvy with digital social-networking platforms, such as Tweeter/Instagram, it took me a while to figure out that actually, I am also doing WFH — work from home. One thing is for sure: it seems that we have suddenly become superhuman in working from home. In pre-Corona times, we always used to have some time in-between two physical meetings to move from one room to the other, or maybe even visit the toilet along the way. Now, it seems that we are expected even not to need the latter break, with online meetings scheduled one right after another! Moreover, to make sure that life does not become too dull, each meeting requires us to navigate through a new platform/medium (software). The current situation has, however, come with a big plus for me and my wife, Nelly. We started exploring the local area, biking through beautiful landscapes around Enschede. At the beginning, after a full day of work at home, we started going out by bike for an hour or so. It gave us some fresh air, at the same time still respecting the social distancing measure. Then, slowly, we started daring to go longer distance in the weekend. One day, we even covered 65+ km. Not bad, huh! I know, this is peanut compared to

the bike-journeys of my predecessor, Jan Willem Polderman. Nevertheless, this was the first such a long bike-journey for me in the last 20 years that I am living in the Netherlands. Who else should I give the credit to, if not to the current lockdown? During this period, we saw one day on news, how the people of the Dutch-Belgian border city of Baarle-Nassau are coping with the different lockdown regulations of the Netherlands and Belgium. Apparently, the international border, indicated by bricks marked with white crosses, goes right through some houses and shops. What should the owner of such a shop do? Keep the Belgium part closed, as per stricter law of Belgium, whereas the Dutch part can remain open? Then during one of our bike-trips, we ourselves came across such an international border marked by bricks with crosses. This time it was the German-Dutch border town of Oldenkott-Winnewick. For me, it was quite interesting to experience it. Even more surprising was a construction site near Rekken, on the very same bike-trip, where a notice board said it was building a Corona Safety-bunker (Schuilkelder). We were totally perplexed. What do they mean by safety-bunker? Is

hiding/staying quarantined inside your own house not safe enough? We reasoned with ourselves that they probably meant a place to keep the Corona-infected people quarantined. But is it not a bit late for that, especially considering the announced completion time to be another 100 days? Then we had a good laugh at the practical joke, when we noticed the board more carefully, with the constructor named as “Prutjemeister BV”; and project-owner being “Stoofie Woofie”. Though we do not know yet what the future has in store for us, I, for one, will keep these smaller but significant happy memories alongside the difficult moments we face now. I wish you all a well deserved, nice, safe and healthy summer ahead.

Puzzle Solution: Geoguessr Sudoku Text: Daan Pluister The QR-code below leads to an interactive map with the locations and pictures used in the puzzle.

Mathematical Memes

Poetry Text: Lars van de Velde Lord of the quarantine Hold your ground! Hold your ground! Sons of Enschede, of Hengelo, my brothers, I see in your eyes the same fear that would take the heart of me. A day may come when we get to go outside again, when we meet our friends and go to all kinds of festivals, but it is not this day. An hour of parties and throwing up, when we drink too much and sing too loud, but it is not this day! This day we stay inside!! By all that you hold dear on this good Earth, I bid you stand, Men of the West!!!

Where are the Abacus members going this summer?

How tuning an instrument becomes a very irrational task Text: Jorg Gortemaker Tuning a music instrument may seem very trivial, for example, to tune a piano, just tune every note to its corresponding frequency and you are done. So then the question becomes, what frequency does every note have. Well, we have defined the note A from the fourth octave to be equal to 440 hertz, or A4 = 440 Hz in scientific pitch notation. Now to find the frequencies of the other notes. To find the frequencies we use harmonics. In music there are intervals and they correspond to different ratios of the harmonics. The harmonics are best described as vibrations of a string of unit length, but with nodes at different points along the string. If the string only has nodes at the end points it is vibrating with its fundamental frequency, say for example 440 Hz, our only known frequency yet. If we place a node at the centre of the string we create the second harmonic, this gives us two times the fundamental frequency, 880 Hz. In music the ratio from fundamental to twice the fundamental is called an octave. So we have found a new note, A5 = 880 Hz. Then if we go up the harmonics, we have three times the fundamental, 1320 Hz, you might think this would be the next octave, but the octave also has to stay the same from A5, so another octave would be 4 times the fundamental, A6 = 1760 Hz. However, we have the fifth, the ratio from 2 times the fundamental to 3 times the fundamental. So now we actually have a different note than just A. Before we continue our search for our search of the frequencies between the octaves of A’s, here is a little side note about the intervals in music. We just found the ratio 3:2 to be a musical fifth, but what is a musical fifth. To best explain this we will use the semitone as a base. An

octave consists of 12 notes, a step between every note is called a semitone, our half a tone. Internationally the semitone is used the most, although I prefer the notation with notes instead, I will yield and use semitones for clarity. So twelve semitone steps from A4 we have A5. A perfect fifth is equivalent to 7 semitones from the fundamental. So from A4, this would give E5. Then the other important ones are: a perfect fourth = 5 semitones, a major third = 4 semitones, a minor third = 3 semitones, a major second = 2 semitones and a minor second = 1 semitone. In the same order from A4 this would give D5, C#5, C5, B4 and B♭4. So now that we have all the intervals we want to find the frequencies to, we need to have their ratios, these are fourth = 4:3, major third = 5:4, minor third = 6:5, major second = 9:8 and minor second = 16:15. So now that we have these, how can we find the frequencies of the notes, we can’t just keep on stacking harmonics, we would never be able to find the frequencies of the lower notes. Luckily we can directly use the ratios, so to find a perfect fifth from A4, E5, we can just multiply the frequency of A4 by 3/2, which gives us E5 = 660 Hz. Alright, let’s actually build a full octave now: B♭4 = 16/15*440 Hz = 469.33.. Hz B4 = 9/8*440 Hz = 495 Hz C5 = 6/5*440 Hz = 528 Hz C#5 = 5/4*440 Hz = 550 Hz D5 = 4/3*440 Hz = 586.66.. Hz D#5 = 45/32*440 Hz = 618.75 Hz E5= 3/2*440 Hz = 660 Hz F5 = 8/5*440 Hz = 704 Hz F#5 = 5/3*440 Hz = 733.33.. Hz G5 = 9/5*440 Hz = 792 Hz G#5 = 15/8*440 Hz = 825 Hz A5 = 2*440 Hz = 880 Hz

Of course, we could build new notes from A4 as long as we would like, but we can also build upon our new found notes and the ratios still hold. So we could go from A4 to A5 by continuously stacking 6 major seconds from A4 until we reach A5, so A5 would be equal to 9/8*9/8*9/8*9/8*9/8*9/8*440 Hz = (9/8)6*440 Hz ≈ 892 Hz which should be equal to A5, but A5 is 880 Hz as we have shown before, so what is going on here? There has to be a mistake somewhere in this calculation, but sadly there is no mistake here, all ratios are correct as they are defined sadly, the system of rational tuning is inherently flawed. How do we fix this? So, in music there are several ways to fix the issue of rational tuning being ambiguous about what frequency every note is, the most used is equal temperament. When fixing this issue, the most used solution is choosing an interval that has the priority and change the tuning of every other note such that the chosen interval with priority will always be correct. In equal temperament the chosen interval is the octave, so to fix the tuning of every other note we use the minor second as a base note, and change it so the octave actually has a ratio of 2:1, the equation we get is as follows: n12*440 Hz = 2*440 Hz n12 = 2 => n =\sqrt[12]{2} Which gives us equal temperament, also, with this fact it is quite easy to show that there is no way to divide the octave such that a rational number is found, because any root of two is irrational.

On the Couch Text: Yanna Kraakman, Timon Veurink D: I stick with the answer that I gave last time. J: Me too, even though I didn’t answer with a theorem back then. L: For me it is Cayley-Hamilton. What’s then your least favourite math theorem? J: hm.. *googles math theorems* I love all theorems. B: I agree. Introduce yourself B: I’m Bozho. D: I’m Daan. J: I’m Jorn. L: Hi, I’m Lavinia. B+D+J: Hallo, Lavinia! Are you seated on a couch? All: no. J: I am seated on a chair. D: me too. B: I am not seated; I’m standing. L: I am on a chair. How long have you been on the couch? D : For about 15 minutes. B: Me too. J: For me maybe a bit less than 15 minutes. L: I have been here for 10 minutes. How long since the last time you went outside? B: 2 hours. D: I did groceries yesterday. J: For me it was yesterday too, probably. I did groceries! L: For me also yesterday. I still need to do groceries today. With whom do you like sitting on the couch most? D: Hey, this is the same question as last time. J: Yes, look at the previous Ideaal! for my answer. D: I don’t want to be inconsistent. With whom do you like laying on the couch most?: L: Well, that changes things. J: I want to lay solo, else there is not enough space. D: I agree. D: But at home you can also just lay in your bed.

L: I guess with Jorg. When sitting on the couch it would be with whoever wants to play a card game. What’s your favourite piece in the Ideaal? J: Still the puzzles. The ones from Stefan Klootwijk, of course. D: Hey, I wanted to say that too. L: For me it is the pen. B: I don’t read the ideaal… What was the best part of your day? D: We conquered our lecture. B: I’m with Daan on this one. We were supposed to have a lecture, but the teacher didn’t show up, so we all turned our cameras on and we chatted in the canvas conference for an hour.. J: I sat on the balcony couch. That was really exciting. L: I did nothing interesting with my day. We spent 2 hours trying to figure out how to make pandas work in python, only to figure out that we are going to use xlrd. What new recipe did you cook during quarentaine? B: I made stamppot for the first time last week. It was good! It was boerenkool. L: I made nothing new, but I made Piadine from scratch. B: I gave up on making lasagne after I failed twice. L: how did you fail?! I’m so confused. D: I didn’t cook anything new.

Are you a cat or dog person? L: Cat! Because cats are cute and I’m spending a lot of quality time now during quarentaine with Jake, which is Jorgs cat. I really like cats. J: Sick. D: I prefer cats. I hate dogs. Cayley or Hamilton? L: Both. B: Neither. I have no opinion, actually. D: I have no preference either. J: I think I said Cayley last time. D: I change my answer to Hamilton, just because I can. What will you eat tonight? J: It’s 1pm, how should I know? B: I don’t know. I am with my parents, so they will cook. L: Pizza! Homemade pizza! Without pineapple, of course. D: I guess an avg’tje (potatoes, meat and veggies), but then the meat will be fake meat, because I’m an environment person. I’m a flexitarian, so I only eat meat at other places, I don’t cook it myself. What are you going to do next? B: I am going to work in 20 minutes. D: I will study. L: I will probably go outside to the garden to eat. D: I might have a walk as well. J: I am going to the estate agent (makelaar) guy to sign a new contract for my new place to live. I am moving to Enschede next month. There will be a basement and a garden!

What’s your favourite math theorem? D: I already answered this question in the previous interview. J: Same for me.

Review: S.V.K.B. Primo Ballerino Text: Imre van Veldhoven We would like to introduce ourselves, we are the board of the student association for classical ballet, Primo Ballerino. As the name already suggests, it is an association for students (and employees!) who like to do classical ballet. Although there already were associations for jazz dance, modern dance, hip hop, ballroom dancing and breakdance, we thought this collection should be extended with an association for classical ballet. After all, as is often said, classical ballet is the basis for all dance forms. One of the founders had been doing classical ballet before his student years, but the other two founders never danced classical ballet before. However, they were so enthusiastic that the three started working and less than a year later Primo Ballerino was a fact. In the meantime it has grown into an association with 46 mem-

bers, divided into three groups that practice classical ballet at three different levels every week.

nl or take a look at our website: primoballerino.utwente.nl.

Why should you become a member of Prima Ballerino? The first reason is of course that classical ballet is the most suitable dance form for mathematicians. Most mathematicians like rules and structure. All these aspect can be found in classical ballet. There is no dance form as structured and compliant to rules as classical ballet. But a much more important reason is the fact that it is very gezellig joining Primo Ballerino. Alongside our ballet lessons we also organize all kinds of other activities. Last year, we had movie nights, enjoyed a delicious Christmas dinner, had fun game nights and many more activities. If you are interested in joining a lesson, do not hesitate to contact us! You can simply send an email to board@primoballerino.utwente.

PRIMO

Ballerino 24