Mathematics for IGCSE & O level - Number (Section 3 - No. 10)

What is the HCF of 84 and 180?

The prime factorization of 84 is 2 x 2 x 3 x 7. The prime factorization of 180 is 2 x 2 x 3 x 3 x 5. The HCF is 2 x 2 x 3 = 12.