It would take a long time to write out all the factors and multiples of 24 and 180 and compare the lists. It would also be easy to make a mistake. A more efficient method is to use prime factors.

Sometimes you are given numbers expressed as a product of prime factors. For example, 8 = 2 3 and 90 = 2 × 3 2 × 5. If you want to find the LCM and HCF in an exam, we can use prime factor form to ...