Question

Find the L.C.M. of the following numbers in which one number is the factor of other:

(a) 5, 20 (b) 6, 18 (c) 12, 48 (d) 9, 45 

What do you observe in the result obtained?

Answer 1

(a) L.C.M. of 5 and 20

= 2 x 2 x 5 = 20

(b) L.C.M. of 6 and 18

2 x 3 x 3 = 18

(c) L.C.M. of 12 and 48

2 x 2 x 2 x 2 x 3 = 48

(d) L.C.M. of 9 and 45

= 3 x 3 x 5 = 45

From these all cases, we can conclude that if the smallest number if the factor of largest number, then the L.C.M. of these two numbers is equal to that of larger number.

Answer 2

(a) L.C.M. of 5 and 20

= 2 x 2 x 5 = 20

(b) L.C.M. of 6 and 18

2 x 3 x 3 = 18

(c) L.C.M. of 12 and 48

2 x 2 x 2 x 2 x 3 = 48

(d) L.C.M. of 9 and 45

= 3 x 3 x 5 = 45

From these all cases, we can conclude that if the smallest number if the factor of largest number, then the L.C.M. of these two numbers is equal to that of larger number.