Do you know the difference between prime and composite numbers? If not, don’t worry! You’ve come to the right place.

In this post, **we’ll talk about what prime and composite numbers are and give you a handy chart you can use to quickly see if something is a composite number.**

## What Is a Composite Number?

**Composite numbers are whole numbers that are greater than 1 and divisible by other whole numbers.**

Here are the questions to ask yourself to decide if a number is composite:

- Is the number a whole number?
- Is the number greater than 1?
- Is the number divisible by whole numbers other than itself?

Let’s apply those questions to two different numbers to see if they are composite or not.

Take the number “4”.

4 is a whole number. It is greater than 1. You can divide 4 by 4. You can also divide 4 by 2, so it’s divisible by other whole numbers.

That means 4 is a composite number.

Let’s look at the number “3”.

3 is a whole number. It’s greater than 1. You can divide 3 by 3. But, you can’t divide 3 by any other whole numbers.

That means 3 isn’t a composite number.

## How to Tell the Difference Between Prime and Composite Numbers

If a number isn’t composite, then it’s prime. **Prime numbers are numbers that are greater than 1 that are only divisible by themselves and the number 1.**

The best way to tell if a number is prime or composite is to perform the divisibility test.

When you use the divisibility test, you check to see if a number is divisible by common prime factors, like 2, 3, 5, 7, 11, and 13.

If you’re testing an even number, start by trying to divide it by 2 to see if it’s composite.

If you’re testing a number that ends with 0 or 5, try to divide it by 5.

If you get a whole number when dividing by any of these common factors, then your number is composite.

If you get a fraction or decimal when dividing by these common factors, then your number is likely prime.

## Composite Number Chart (1-100)

Here is a handy composite number list to reference. All of the numbers in blue are composite numbers.

## Prime Number Chart (1-100)

Here’s an easy-to-reference prime number list. All of the numbers in red are prime numbers.

## Final Thoughts

It’s important to know whether a number is prime or composite so you can understand whether or not the number is divisible.

Remember, ask yourself these questions to tell if a number is a composite number or not:

- Is the number a whole number?
- Is the number greater than 1?
- Is the number divisible by whole numbers other than itself?

## What’s Next?

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