3 Tania is writing the number 70 using multiplication facts. 70 = 7 × 10 She then notices that 10 can also be written as a multiplication fact. 70 = 7 × 5 × 2 composite prime The numbers 2, 5 and 7 are prime. So all composite numbers are made up of prime numbers.
1 Write a multiplication fact to show that the number 18 is a composite number.
2 Write all of the prime numbers between 10 and 20.
Find the next prime number after: (a) 8 (b) 20
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(c) 50
4 Write down the one number from each group that is not prime . (a) 1 3 5 7 (b) 11 21 31 41 5 Write down the number from each group that is prime. (a) 2 4 6 8 (b) 5 10 15 20
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9781380050717__text.indb 6
28/04/2022 12:11
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