Question

find the LCM and HCF of the following integers by applying the prime factorisation method
= 12,15 and 21

Answer 1

12 = 2 × 2 × 3

15 = 3 × 5

21 = 3 × 7

HCF = 3

LCM = 2 × 2 × 3 × 5 × 7

LCM = 420

Answer 2

12=2,2,3,15=3,5,21=3,7 hcf=3 lcm=320