Question

Find the LCM and HCF of the following integers by applying the prime factorisation method.
(i) 12,15 and 21

Answer 1

Hey

12 = 2 x 2 x 3

15 = 3 x 5

21 = 3 x 7

HCF :-

The HCF of 12,15 and 21 is 3

LCM :-

LCM = 2 x 2 x 3 x 5 x 7 = 420

The LCM of 12,15 and 21 is 420

Answer 2

LCM of 12=2^2*3

" " " " " " 15=3*5

" " " " "21=3*7

then, LCM of 12,15,21=2^2*3*5*7=420

HCF of 12,15,21=3