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

Answer

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?

Answer

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!