Question

Find the HCF of the following numbers: 20, 28, and 36.

Answer 1

The HCF of 20, 28 and 36 can also be found by prime factorisation of these numbers as follows:

Thus,
20 = 2 × 2 × 5
28 = 2 × 2 × 7
36 = 2 × 2 × 3 × 3.

The common factor of 20, 28, and 36 is 2 (occurring twice).

Thus, HCF of 20, 28 and 36 is 2 × 2 = 4.