How to explain find the HCF in LCM and HCF to your student
27 October 2026
Understanding the Highest Common Factor (HCF) is an important skill for 11+ maths. It helps children spot the biggest number that divides exactly into two or more numbers. This example makes it clear and simple to follow.
Example question
Find the Highest Common Factor (HCF) of 18 and 24.
Step 1: List the factors of 18.
The factors of 18 are 1, 2, 3, 6, 9, 18.
Step 2: List the factors of 24.
The factors of 24 are 1, 2, 3, 4, 6, 8, 12, 24.
Step 3: Find the common factors.
The numbers that are in both lists are 1, 2, 3, 6.
Step 4: Pick the biggest common factor.
The largest number in both lists is 6.
Answer: The HCF of 18 and 24 is 6.
Key insight: Once your child can find the HCF, they can tackle similar questions with confidence. Practice questions on this topic will help them recognise common factors quickly and build strong number sense.
