**Factor pairs** *KS2 Revision*

## What you need to know

**Things to remember:**

- A factor is a number that divides another number exactly.
- The answer to the division is also a factor.
- The answer and the number you divided by are called a “factor pair”.
- Numbers often have more than 1 factor pair.
- A square number has a factor that is paired with itself.

A factor is a number that divides another number and gives a whole number. For example, because 32\div8=4, then 8 is a factor of 32. This means that 4 is a factor of 32 as well. We call these two numbers, 4 and 8, a factor pair.

When finding a factor pair, we are really just looking for two numbers that multiply together to make the original number.

*Find a factor pair of 48.*

We can divide 48 by 6, 48\div6=8, so we get a factor pair of 6 and 8. To check this factor pair, we can multiply them. 6\times8=48, so these are a factor pair of 48. The factor pairs of 48 are:

1 and 48

2 and 24

3 and 16

4 and 12

6 and 8

Prime numbers are special, they only have 1 factor pair; 1 and the number itself. 17 is a prime number because the only factor pair is 1 and 17.

## Example Questions

**Question 1:** Find a factor pair of 36

Factor pairs of 36 are:

1 and 36

2 and 18

3 and 12

4 and 9

6 and 6

**Question 2:** Is 28 a prime number?

Remember, a prime number only has 1 factor pair. Does 28 have 1 factor pair?

**Factors of 28:**

1 and 28

2 and 14

4 and 7

28 has more than 1 factor pair, so is not prime!