Highest Common Factor KS3 Challenge

The highest common factor (HCF) is found by finding all common factors of two numbers and selecting the

• largest one
• smallest one
• middle one

Calculate the HCF of 30 and 18

Calculate the HCF of 40 and 24

Calculate the HCF of 15 and 35

Calculate the HCF of 14 and 25

Calculate the HCF of 108 and 144

Calculate the HCF of 18, 54 and 60

Calculate the HCF of 42 and 90

Calculate the HCF of 72 and 80

Calculate the HCF of 70 and 280