## 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!