How do you find the LCM of 7 12 and 21?

Answer 1

Method to find the LCM of two numbers a & b:

1- Find the GCF(Greatest Common Factor) of a & b.

2- Find the product of a & b.

3- Divide the product of a & b by the result obtained in step 1.

STEP 1:

Greatest common factor can be found by the method of prime factorization.

Prime factorization of 121 = 11 x 11

Prime factorization of 132 = 11 x 12

GCF(121, 132) = 11

STEP 2:

Product of 121 & 132 = 15972

STEP 3:

LCM(121, 132) = 15972/11 = 1452

Answer 2

Ignore 7, since it's a factor of 21.

2 x 2 x 3 = 12

3 x 7 = 21

Combine the factors, eliminating duplicates.

2 x 2 x 3 x 7 = 84, the LCM

Answer 3

It is: 3564