Question

tell the LCM 3, 5, 15, 10, 20 AND 21
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Answer 1

LCM of 3, 5, 15, 10, 20 & 21 is 420

List all prime factors for each number.

Prime Factorization of 3 :

3 is prime => 31

Prime Factorization of 5 :

5 is prime => 51

Prime Factorization of 10 is:

2 x 5 => 21 x 51

Prime Factorization of 15 is:

3 x 5 => 31 x 51

Prime Factorization of 20 is:

2 x 2 x 5 => 22 x 51

Prime Factorization of 21 is:

3 x 7 => 31 x 71

Multiply these factors together to find the LCM.

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