HCF and LCM worksheets

About this worksheet

The HCF (highest common factor) of two numbers is the biggest number that divides both. The LCM (lowest common multiple) is the smallest number that both divide. For 12 and 18 the HCF is 6 and the LCM is 36.

Tips for parents and teachers

• Use prime factorisation or the division method, whichever the school teaches, and keep to one until it is sure.
• A useful check: HCF times LCM equals the product of the two numbers. 6 times 36 = 216 = 12 times 18.
• The HCF can never be bigger than the smaller number; the LCM can never be smaller than the bigger number.

Ready settings by class

• HCF and LCM, smaller numbers Class 5
• HCF and LCM, bigger numbers Classes 6 to 8

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