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Identify if a number is prime

This math skill teaches how to identify if a number is prime by checking if it has any divisors other than 1 and itself. It involves dividing the number by known prime numbers, stopping if the square of a prime exceeds the number. If no divisors are found, the number is prime.

Learn identify if a number is prime

Teaching Transcript

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Let's check if either 37 or 35 are prime

Check if it divides by any other prime. Neither divides by 2

Or by 3

35 divides by 5, so we know it's not a prime. That means it is a composite number, made up of factors other than 1 and itself.

37 does not divide by 7

Since 7 x 7 would be 49, and that's already larger than 37, we can stop here

37 is a prime since it has no factors except for itself and 1

Skill Practice

Identify if a number is prime

Test your understanding of identify if a number is prime by practicing it! Work through the below exercises to use it in practice.