HCF & LCM
Maths: Edexcel IGCSE Higher, topic 1.1.6
Highest Common Factor (HCF)
The highest common factor is the highest factor that two numbers have. How to find the highest common factor (HCF) of 21 and 28:
Write the factors of 21
Write the factors of 28
HCF is the highest number which appears in both lists: 7
Lowest Common Multiple (LCM)
The lowest common multiple is the lowest multiple that two numbers both have. What is the lowest common multiple (LCM) of 6 and 8?
Write out multiples of 6
Write out multiples of 8
Find the lowest number on both lists
Test yourself on HCF & LCM
Factors of 18
What is the lowest common multiple of 10 and 5?