Question

find the Lcm and hcf of 12,15,and 21 by applying the prime factorisation method

Answer 1

12=2×2×3

15=5×3

21=7×3

HCF=3

LCM=2²×3×5×7=420

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Answer 2

Given: Three numbers-  12, 15 and 21

To find: LCM and HCF of given numbers by prime factorization method

Solution:

Using prime factorization method, the given numbers can be expressed as:

12 = 2 × 2 × 3

15 = 3 × 5

21 = 3 × 7

LCM is the product of maximum frequencies of all the prime factors of given numbers.

LCM = 2 × 2 × 3 × 5 × 7 = 420

HCF is the product of common prime factors of given numbers.

HCF = 3 (3 is the only common factor)

Hence, LCM is 420 and HCF is 3.