Is 15 a composite number?

The second way of answering Is 15 a composite number? is to try to divide 15 by a series of smaller prime numbers, using the how to identify whole numbers that are prime and composite method.

Using the list of prime numbers that are smaller than 15, do the following divisions.

List of prime numbers to 15

• Divide 15 by 2 - is 15 divisible by 2? The answer is no.

• Divide 15 by 3 - is 15 divisible by 3? The answer is yes. 15 divided by 3 is 5.

That means 1, 3, 5 and 15 are factors of 15 making 15 a composite number, not a prime number.