St Michael's CE Primary School Blog

PRIME OR NOT Prime? That iS THE QUESTION

In Numeracy, Year five have been learning about multiples, factors, prime numbers and prime factors. Here, the children are creating a table that will help them identify prime numbers less than 100.

  • First we coloured in 1, because all prime numbers are greater than 1.
  • Number 2 is a prime number. In fact it is the only even one. So we kept it, but coloured in all the multiples of 2 (i.e even numbers).
  • Number 3 is also a prime, so again we kept it and coloured in all the multiples of 3.
  • The next number not coloured in was 5 (because 4 was already coloured in), so we kept it and coloured in all the multiples of 5.
  • The final number left in the first row was 7 (it’s prime so we kept it) and coloured in all the multiples of 7.
  • FINISHED! All the ‘surviving’ numbers that are not coloured in on the grid are PRIME NUMBERS!
There you have it. There are 25 prime numbers between 1 and 100! Well done Year 5.
Did you know that whole numbers that are not prime numbers are called composite numbers? We hope you have learnt something new from our blog today.

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