# Difference Prime and Composite Numbers

Let's look at the rules for prime and composite numbers. All whole numbers that are greater than one can be classified as prime or composite numbers.

Prime numbers have only factors one and itself. A composite number has other factors other than itself and one. So let's look at some examples. Let's look at 4 and 5.

Four is divisible by 1 and four is divisible by 2 so four is a composite number.

Five is divisible by 1 but it is odd so it is not divisible by 2 or any other number so 5 is prime

So let's look at some that are a little bit larger. Let's look at thirty and thirty-one.

30 is divisible by 1

It is, even so, this means it is divisible by 2 so you already know it is composite.

But it also is divisible by 3 and 5.

So 30 is composite.

31 is divisible by 1

It is not divisible by 2 or 3 or any other number so it is prime.

Interesting fact, two is the only even prime number.

Any other number that is even will be a composite number because it is divisible by two.

So in summary,

Prime numbers are only divisible by two numbers 1 and itself.

Composite numbers are divisible by factors other than itself and one.