1. 18 2 9 3 3 Find the prime factors of 18.
To find prime factors draw a factor tree.
Split 18 into a pair of factors. 18 2 9
Split 9 into a pair of factors.
2 is a prime number – so this branch is finished 3 3
The prime factors of 18 are 2 x 32
The prime factors of 18 are 2 x 3 x 3

2. 18 3 6 2 3 Find the prime factors of 18.
Split 18 into a pair of factors. 18 3 6
Split 6 into a pair of factors.
3 is a prime number – so this branch is finished 2 3
The prime factors of 18 are 2 x 32
The prime factors of 18 are 2 x 3 x 3

3. 20 2 10 2 5 Find the prime factors of 20.
Split 20 into a pair of factors. 20 2 10
Split 10 into a pair of factors. 2 5
The prime factors of 20 are 2 x 2 x 5
The prime factors of 20 are 22 x 5

4. 20 4 5 2 2 Find the prime factors of 20.
Split 4 into a pair of factors. 2 2
The prime factors of 20 are 2 x 2 x 5
The prime factors of 20 are 22 x 5

5. 24 2 12 2 6 2 3 Find the prime factors of 24.
The prime factors of 24 are 2 x 2 x 2 x 3
The prime factors of 24 are 23 x 3 2 12 2 6 2 3

6. 24 2 12 3 4 2 2 Find the prime factors of 24.
The prime factors of 24 are 2 x 2 x 2 x 3
The prime factors of 24 are 23 x 3 2 12 3 4 2 2

7. 24 3 8 2 4 2 2 Find the prime factors of 24.
The prime factors of 24 are 2 x 2 x 2 x 3
The prime factors of 24 are 23 x 3 3 8 2 4 2 2

8. 24 4 6 2 2 2 3 Find the prime factors of 24.
The prime factors of 24 are 23 x 3
The prime factors of 24 are 2 x 2 x 2 x 3

9. Find the prime factors of these numbers:12 16 30 22 28 64
100
125
240
144
Remember to find prime factors you draw a factor tree!

10. The prime factors of 12 are 2x2x3 or 22 x 36 3 4 2 3 2 2
The prime factors of 12 are 2x2x3 or 22 x 3

11. The prime factors of 16 are 2x2x2x2 or 248 2 2 2 2 2 2 4 2 2
The prime factors of 16 are 2x2x2x2 or 24

12. The prime factors of 30 are 2 x 3 x 515 5 6 3 5 2 3
The prime factors of 30 are 2 x 3 x 5

13. The prime factors of 22 are 2 x 11

14. The prime factors of 28 are 2x2x7 or 22 x 714 4 7 2 7 2 2
The prime factors of 28 are 2x2x7 or 22 x 7

15. The prime factors of 64 are 2x2x2x2x2x2 or 268 8 2 4 2 4 2 2 2 2
The prime factors of 64 are 2x2x2x2x2x2 or 26

16. The prime factors of 100 are 2x2x5x5 or 22 x 5220 4 5 2 2
The prime factors of 100 are 2x2x5x5 or 22 x 52

17. The prime factors of 125 are 5x5x5 or 53

18. The prime factors of 240 are 24 x 3 x 510 24 4 2 6 5 2 2 2 3
The prime factors of 240 are 24 x 3 x 5

19. The prime factors of 144 are 24 x 3212 12 3 4 3 4 2 2 2 2
The prime factors of 144 are 24 x 32