Question

Find the LCM of the following by common division method : a) 54, 60 , 84 Ans: b) 126, 175 , 420 , 630 Ans:

Answer 1

Answer:

a. 7560

b. 9450

Step-by-step explanation:

a )54,60,84/(2) = 27,30,42 /(3) = 9,10,14 /(2)=9,5,7

Hence 2*3*2*9*5*7 = 3780

b) 126, 175,420 ,630/(7)=18,25,60,90/(9) = 2,25,60,10/(5)=2,5,12,2/(2)=1,5,6,2/(2)=1,5,3,1

Hence 7*9*5*2*1*5*3*1 = 9450

Answer 2

Step-by-step explanation:

a)

2 54, 60, 84

2 27, 30, 42

3 27, 15, 21

9, 5, 7

no more common factors

LCM = 2 x 2 x 3 x 9 x 5 x 7

= 2 x 2 x 5 x 3 x 9 x 7

= 20 x 3 x 63

= 60 x 63

= 3780

b)

2 126, 175, 420, 630

3 63, 175, 210, 315

3 21, 175, 70, 105

5 7, 175, 70, 35

7 7, 35, 14, 7

1, 5, 2, 1

no more common factors

LCM = 2 x 3 x 3 x 5 x 7 x 5 x 2

= 2 x 5 x 2 x 5 x 3 x 3 x 7

= 10 x 10 x 63

= 6300