Question

Find the L.C.M. of the following group of numbers, using

1. the prime factor method and
2. the common division method

34, 85 and 51

Answer 1

L.C.M. of 34, 85 and 51

i. By prime factors
Prime factors of 34 = 2 x 17 = 2¹ x 17¹
Prime factors of 85 = 5 x 17 = 5¹ x 17¹
Prime factors of 51 = 3 x 17 = 3¹ x 17¹
∴ L.C.M. of 34, 85 and 51 = 2¹ x 5¹ x 3¹ x 17 = 510

ii. By common division method

2	34,	85,	51
17	17,	85	51
	1,	5,	3

∴ L.C.M. of 34, 85 and 51 = 2 x 17 x 5 x 3 = 510