Numbers and the number system
Rounding Challenge
Solving mathematical problems
You will need: • set of 1–9 digit cards
Shuffle a set of 1–9 digit cards. Choose the top four cards. Use these cards to make different 2-, 3- and 4-digit numbers. Then round each: • • •
2-digit number to the nearest ten 3-digit number to the nearest ten and hundred 4-digit number to the nearest ten, hundred and thousand.
4 7 2 9
Numbers and the number system
Factors Challenge Investigate which numbers less than 100 have proper factors that are only even numbers. Investigate which numbers less than 100 have proper factors that are only odd numbers.
Think about … For the ‘Challenge’, make sure that you use the four digit cards to create at least six 2-digit numbers, six 3-digit numbers and six 4-digit numbers.
For the ‘What if?’ task, make sure that you use the four digit cards to create at least three decimals with 1 decimal place (tenths), and three decimals with 2 decimal places (hundredths)
What if ? What if you use the four digit cards to make different decimal numbers for tenths and hundredths? Multiply each of the decimal numbers by 10 and 100. Divide each of the decimal numbers by 10. Round each decimal with: • • 8
1 decimal place to the nearest whole number 2 decimal places to the nearest tenth and whole number.
9∙2 × 10 = 9∙2 × 100 = 9∙2 ÷ 10 = 9∙2 rounded to the nearest tenth is …
9∙2 27∙4 47∙29 7∙42
Solving mathematical problems
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Think about … A factor is a whole number that divides exactly into another whole number without a remainder.
Proper factors of a number are all its factors except 1 and the number itself.
A prime number is a whole number greater than 1 that can’t be divided by another whole number, except for itself and 1.
A factor of a whole number that is also a prime number is called a prime factor.
What if ? 20 : 1, 2, 4, 5, 10 and 20 20 has two prime factors: 2 and 5.
When you’v e finished, tur n to page 80.
Investigate other numbers less than 100 that have two prime factors.
When you’v e finished, tur n to page 80. 9