Question

Find the LCM and HCF of the following integers by applying the prime factorisation method.` (i) 12,15 and 21           (ii) 17, 23 and 29         (iii)  8,9 and 25`

Answer 1

1)12,15,21
factors
12=2*2*3
15=3*5
21=3*7
HCF=3
LCM=3*2*2*5*7=420
2)17,23,29
factors
17=1*17
23=1*23
29=1*29
HCF=1
LCM=17*23*29=11339
3)8,9,25
factors
8=2*2*2
9=3*3
25=5*5
HCF=1
LCM=8*9*25=1800