Question

find H.C.F and L.C.M of 12,15 and 21 by prime factorisation method

Answer 1

12, 15, 21

12 = 2² $\times$ 3

15 = 3 $\times$ 5

21 = 3 $\times$ 7

L.C.M = 2² $\times$ 3 $\times$ 5 $\times$ 7 = 420

H.C.F = 3