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Percentages

What does “per cent� mean? It means divided by 100, like this circle. So when it says what is 50% of 200? You have to divide 200 by 100 and then multiply by 50.


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Starting at the arrow, colour 25 segments in red, 25 in blue and 25 in green.


0%/ 100 %

25 %

75 %

50 %

What do you notice about these 4 segments ? 7


Using what you have worked out from the previous page how will you answer the following questions? How did you work this out?

What is 50% of 10?

How did you work this out?

What is 25% of 20?

How did you work this out?

What is 75% of 12?

How did you work this out?

What is 25% of 16?

How did you work this out?

What is 50% of 10?


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At the start we said that to find a percentage of something you divide by one hundred then multiply by what you want. You might think that dividing by hundred would be hard but it isn’t. You just move the decimal point to the left, once divides by 10, twice by 100. Divide 20 by 10

20

.00

becomes 2.00

Move the decimal point 1 place to the left. (BTW that would be 10%) Divide 200 by 100

200

. 0 0 becomes 2

Move the decimal point 2 places to the left. That finds 1%. So if you want to find 40% of 200 multiply 2 by 40 = 80. 13% of 200 multiply 2 by 13 = 26 and so on.


Show your working

What is 1% of 250 ?

24%?

What is 1% of 300 ?

15%?

What is 1% of 20 ?

21%?

What is 1% of 500 ?

20%?

What is 1% of 75 ?

10%?

What is 1% of 40 ?

25%?

What is 1% of 450 ?

30%?

What is 1% of 60 ?

5%?

What is 1% of 150 ?

9%?

What is 1% of 100 ?

15%?

What is 1% of 25 ?

20%?

What is 1% of 450 ?

35%?

What is 1% of 250 ?

45%?

What is 1% of 250 ?

75%?

What is 1% of 250 ?

55%?

What is 1% of 250 ?

65%?

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You can use a calculator to solve the following. A coat costs £20, but then we have to add on 20% VAT. How much will it cost in total? How did you work this out?

A meal in the restaurant cost £25 but they add a 10% service charge. How much do you have to pay? How did you work this out?

You book a flight to Paris for £80 but 5% airport tax has to be added, how much has to be paid? How did you work this out?


A cap costs £20, but it is reduced by on 10%. How much will it cost in total? How did you work this out?

A shop is selling dvds for £10 but if you buy 4 there is a 20% reduction. How much do you have to pay? How did you work this out?

You book a flight to Paris for £80 but there is a sale on with 5% off, how much has to be paid? How did you work this out?

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While we are using a calculator here is a short cut for finding a percentage. To find 35% of 250 enter 250 into the calculator, enter x and then .35 . Press = and you should get the answer 87.5. Clear this. Now enter 250, รท by 100 to find 1% and then multiply by 35 to find 35%, what is your answer? Use the shortened method to find the following percentages and write down your keystrokes. For example: 45% of 350 = 157.5 Keystrokes 350 x .45 = 50% of 270 = Keystrokes 75% of 300 = Keystrokes 33% of 200 = Keystrokes


Percentages