What is the HCF of 21 and 36?

Answer 1

To find this, you first need to split the numbers down into their prime factors. In this case you get:

21 = 3x7

36 = 2x2x3x3

The next step is to identify any common prime factors. In this case the only common prime factor is 3. Therefore the HCF of 21 and 36 is 3.