# 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

#### Using prime factorisation method:

**(i) 12, 15 and 21**

Factor of 12=2×2×3

Factor of 15=3×5

Factor of 21=3×7

HCF** **(12,15,21)=3

LCM (12,15,21)=2×2×3×5×7=420

**(ii) 17, 23 and 29**

Factor of 17=1×17

Factor of 23=1×23

Factor of 29=1×29

HCF** **(17,23,29)=1

LCM (17,23,29)=1×17×23×29=11,339

**(iii) 8, 9 and 25**

Factor of 8=2×2×2×1

Factor of 9=3×3×1

Factor of 25=5×5×1

HCF (8,9,25)=1

LCM (8,9,25)=2×2×2×3×3×5×5=1,800