The Sieve of EratosthenesThe Sieve of Eratosthenes
A Prime Number is a number which only has itself and one as factors.
Eratosthenes was a Greek mathematician who discovered a way of "sieving" out the Prime numbers.
Strike out the twos
Strike out the threes
The Sieve of Eratosthenes
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First draw out a 100 square Then cross out 1. 1 is NOT a Prime Number - it only has one factor.
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