Question

Write the lcm of the numbers shown with solution

1. 21 and 35
2. 56 and 64
3. 72 and 81
4. 32, 48 and 60
5. 27, 38 and 45
6. 120, 160 and 180
7. 45 and 60

Answer 1

1) 21 = 3 × 7

35 = 5 × 7

LCM = 3 × 5 × 7 = 105

2) 56 = 2 × 2 × 2 × 7

64 = 2 × 2 × 2 × 2 × 2 × 2

LCM = 2 × 2 × 2 × 2 × 2 × 2 × 7 = 448

3) 72 = 2 × 2 × 2 × 3 × 3

81 = 3 × 3 × 3 × 3

LCM = 2 × 2 × 2 × 3 × 3 × 3 × 3 × 3

= 1,944

4) 32 = 2 × 2 × 2 × 2 × 2

48 = 2 × 2 × 2 × 2 × 3

60 = 2 × 2 × 3 × 5

LCM = 2 × 2 × 2 × 2 × 2 × 3 × 5 = 480

5) 27 = 3 × 3 × 3

38 = 2 × 19

45 = 3 × 3 × 5

LCM = 2 × 3 × 3 × 3 × 5 × 19 = 5,130

6) 120 = 2 × 2 × 2 × 3 × 5

160 = 2 × 2 × 2 × 2 × 2 × 5

180 = 2 × 2 × 3 × 3 × 5

LCM = 2 × 2 × 2 × 2 × 2 × 3 × 3 × 5

= 1,440

7) 45 = 3 × 3 × 5

60 = 2 × 2 × 3 × 5

LCM = 2 × 2 × 3 × 3 × 5 = 540