In mathematics, factors are two whole numbers that can be multiplied to create a product. In the case of this post, the product is 18.

So, what are the factors of 18?

## Factors of 18

There are many numbers that you can multiply to make 18. The 6 factors for 18 are:

- 1
- 2
- 3
- 6
- 9
- 18

### How to Factorise 18

To find the factors, divide 18 by all whole numbers starting with 1. Stop when the result is smaller than the number you are dividing by. Only results that include whole numbers are factors.

Rules:

- Even numbers are always divisible by 2
- If a number ends in 0 or 5, it is divisible by 5

## Factors of 18 in Pairs

**Factor pairs are the two numbers that can be multiplied to make the product, 18. **All factor pairs for 18 are as follows:

- 1 × 18= 18
- 2 × 9= 18
- 3 × 6= 18

These positive factors are the most commonly accepted answer; however, there are also negative factors of 18.

The negative factors of 18 are: -1, -2, -3, -6,-9, -18

The negative factor pairs are:

- -1 × -18= 18
- -2 × -9= 18
- -3 ×- 6= 18

## Prime factorization of 18

To understand prime factors, you must know about prime numbers. **A prime number is a number that is greater than 1 and cannot be divided into smaller numbers.** (They can only be divided by 1 and the number itself.)

Prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19, 23, etc.

Prime factorization is when a product is broken down into all of its prime factors.

The prime factorization of 18 is:

- 2 x 3 x 3 = 18

To get this number, we start with the smallest prime factor that 18 is divisible by: 2.

- 18 divided by 2 is 9 (9 is not a prime number)
- 9 divided by 3 is 3 (3 is a prime number)

It can also be written as exponents.

**The prime factors of 18 are: 2 x 3 x 3 = 2 × 3 ^{2} = **18

## Common factors of 18

The **common factors of two (or more) numbers are the factors that the numbers have in common**. For example:

The factors of 18 are: 1, 2, 3, 6, 9, 18

The factors of 27 are: 1, 3, 9, 27

Their common factors are: 1, 3 and 9

The **greatest common factor** is the largest of the common factors.

- What is the greatest common factor of 18 and 24?

The factors of 18 are: 1, 2, 3, 6, 9, 18

The factors of 24 are: 1, 2, 3, 4, 6, 8, 12, 24

The greatest common factor is: 6

- What is the greatest common factor of 18 and 12?

The factors of 18 are: 1, 2, 3, 6, 9, 18

The factors of 12 are: 1, 2, 3, 4, 6, 8, 12

The greatest common factor is: 6

## FAQ

**What are all the factors of 18?**

Factors of 18 are: 1, 2, 3, 6, 9, and 18.

## Related:

What are the factors of 24?