Highest Common Factor

Find the HCF of 9 and 15

• 3

• 2

• 5

• 9

Find the HCF of 12 and 28

• 4

• 3

• 6

• 12

Find the HCF of 56 and 42

• 14

• 7

• 2

• 6

Find the HCF of 27 and 63

• 9

• 7

• 3

• 11

Find the HCF of 16 and 64

• 13

• 4

• 9

• 8

Find the HCF of 45 and 81

• 5

• 9

• 20

• 8

Where do you need to start when finding the HCF?

• Adding the numbers togheter

• Create a factor tree

• Multiply the results.

• Divide the prime numbers found.

What is the HCF of 64 and 78

• 8

• 24

• 2

• 1

What are the factors of 24 and 32

• 8,1,2,4

• 8,2,3,4

• 4,5,9,7

• 2,3,1,8

What are the coomon factoes betwen 45 and 60?

• 4,2,3,15

• 30,14,3,2

• 1,3,5,15

• 2,5,1,6