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Here's a reminder of what defines a prime number:

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This puzzle provides pupils with practice recognising prime numbers. If pupils have access to a calculator they may need to devise a procedure for checking whether a number is prime or not. It is expected that the pupils doing this activity will begin to recognise the first 25 prime numbers represented here. It's probably a good idea to do the Prime Numbers Jigsaw before attempting this activity.

#### Factor Trees

Create factor trees to find the prime factors of the given numbers.

Transum.org/go/?to=factortrees

#### Sieve of Eratosthenes

A self checking, interactive version of the Sieve of Eratosthenes method of finding prime numbers.

Transum.org/go/?to=sieve

#### Prime Square

Drag the numbers into the red cells so that the sum of the three numbers in each row and each column is a prime number.

Transum.org/go/?to=psquare

#### Scallywags and Scoundrels

Arrange the scallywags and scoundrels on the chairs so that the numbers of any two sitting next to each other add up to a prime number.