Question

Which numbers are prime numbers? Check all that are true. 56 12 13 20 7 none of the above

Answer 1

13 and 7 are prime numbers.

Explanation:

Prime numbers are those which can be divide by 1 or themselves. So, 13 and 7 are prime because they can only be divided by 1 and themselves. 56, 12 and 20 can be divided by 1,2,4 so they are not prime.

Answer 2

Prime numbers

By definition, a prime number is a number that only has 2 factors, which are 1 and itself.

Out of the given numbers, only 13 and 7 have 2 factors; the rest have 3 or more. 20, for example - it can be divided by 1, 2, 4, 5, 10, and 20.

As for 12, it's divided by 1, 2, 3, 4, 6, and 12. That's a lot!

To summarize, primes have 2 factors - 1 and themselves.