Maths dictionary

What are HCF and LCM?

The highest common factor (HCF, or GCF) is the biggest number that divides two numbers exactly. The lowest common multiple (LCM) is the smallest number that both numbers divide into.

Definition

The highest common factor (HCF, or GCF) is the biggest number that divides two numbers exactly. The lowest common multiple (LCM) is the smallest number that both numbers divide into.

Example

For 12 and 18, the HCF is 6 and the LCM is 36.

Tip

Use the HCF to simplify fractions and the LCM to add fractions with different denominators.

Practise it

Worksheets: Highest common factor and lowest common multiple (Grade 6)
Online maths practice

Quick check: try these

Work each one out on paper, then tap the question to see the answer.

The LCM of 18 and 19 is
Answer: 342
The LCM of 22 and 16 is
Answer: 176
The HCF (GCF) of 4 and 36 is
Answer: 4
The HCF (GCF) of 22 and 35 is
Answer: 1

Learn it in depth

HCF and LCM is part of HCF and LCM for Class 6: notes, formulas, solved examples with every step, common mistakes and ten practice questions with answers. Want a teacher to go through it with you? See Class 6 maths tuition.

Related words

Factor, Multiple, Equivalent fraction