Question

Is 10 a prime or composite?

Answer 1

`10` is a composite number.

Explanation:

To check if a number `n` is prime, test if `n` is divisible from any of the numbers from `2` all the way up to `sqrtn`. If `n` isn't divisible, by any of the numbers, then `n` is prime.

For `10`, we want to test all the whole numbers between `2` and `sqrt10` which is about `3.2`. We will need to test `2` and `3`:

Is `10` divisible by `2`?

Yes, because `10div2=5`.

This fact is enough to prove that `10` is not prime, so we can stop now. This means that `10` is composite.