Question

Find the LCM of number by prime factorization 42, 36 and 21​

Answer 1

I have explained the working of the sum in the picture.

LCM=2×3×3×2×7

=36×7

=252

Answer 2

Solution

Hey mate here is your answer,

$3 |42 \: \: 36 \: \: 21| \\ 7 |14 \: \: 12 \: \: \: 7| \\ 2 | \: 2 \: \: \: 12 \: \: \: 1| \\ \: \: | \: 1 \: \: \: \: \: \: 6 \: \: 1|$

Therefore,

L.C.M of 42,36 and 21 is 3×7×2×1×1×6=252

L.C.M by Prime factorization method

$42 = 7 \times 3 \times 2 \\ 36 = 3 \times 3 \times 2 \times 2 \\ 21 = 7 \times 3$

Therefore L.C.M= 7×3×3×2×2=252