Question

Compute the LCM of 30 and 12 using prime factor method.

Answer 1

Using the prime factor method to find L.C.M:

Express the given numbers as a product of prime factors as follows:

$30=2\times 3\times 5$

$12=2\times 2\times 3$

L.C.M = Product of all prime factors with highest number of instances of each factor.

Here, the prime factors are 2, 3 and 5.
3 and 5 occur once in the prime factorisation, while 2 occurs twice. Therfore, we multiply : ( 2 $\times$ 2 ) $\times$ 3 $\times$ 5

Required L.C.M = $2\times 2$ $\times$ $3$ $\times$ $5$ = 60