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 ...

The highest common factor (abbreviated to HCF) is the largest number that goes into two or more subject-numbers. For example, the common factors of 40 and 16 are 2, 4 and 8. The HCF of 40 and 16 ...