Worked out example

Find the LCM of the following set of numbers

using prime factorization method:

a. 15, 18 

b. 2, 7, 9

c. 6, 12, 18, 36

Solutions

a). 15 = 3 x 5 

18 = 2 x 3 x 3

The LCM is 2 x 3 x 3 x 5 = 2 x 9 x 5 

= 2 x 45 

= 90

b). 2 = 2 x 1

 7 = 7 x 1 

9 = 3 x 3

The LCM is 2 x 7 x 3 x 3 = 126

c). 6 = 2 x 3 

12 = 2 x 2 x3 

18 = 2 x 3 x 3 

36 = 2 x 2 x 3 x 3

The L.C.M is 2 x 2 x 3 x3 = 4 x 9 = 36