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# Exercise 2.2 (Least Common Multiple LCM)

Text Book Back Exercises Questions with Answers, Solution : 5th Maths : Term 2 Unit 2 : Numbers : Exercise 2.2 (Least Common Multiple LCM)

Exercise 2.2

(i) The number divisible by 5 with no remainder

a. 14

b. 535

c. 447

d. 316

(ii) Pick the number which is not a multiple of 6.

a. 18

b. 26

c. 72

d. 36

(iii) The common multiple of 4 and 8 among the given number is.

a. 32

b. 84

c. 68

d. 76

(iv) Factors of 6

a.1, 2, 3

b. 1, 6

c. 1, 2, 3, 6

d. 2, 3

Answer: c. 1, 2, 3, 6

v) Multiple of 9 is

a.79

b. 87

c. 29

d. 72

2. Fill in the blanks:

(i) Factors of 7 1 , 7

(ii) The only even prime number is 2

(iii) L.C.M of 4, 12 12

(iv) L.C.M of 5, 15 15

(v) The numbers which divides 35 without reminders are 1, 5, 7

3. Write down the factors of the given numbers.

(i) 25

(ii) 36

(iii) 14

(iv) 16

(v) 12

i) The factors of 25 are 1, 5, 25

ii) The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36

iii) The factors of 14 are 1, 2, 7, 14

iv) The factors of 16 are 1, 2, 4, 8, 16

v) The factors of 12 are 1, 2, 3, 4, 6, 12

4. Draw a picture of factor tree.

(i) 18

(ii) 33

(iii) 16

(iv) 50 5. Write down the first 5 multiples of the given numbers.

(i) 7

i) The first 5 multiples of 7 are

7, 14, 21, 28, 35

(ii) 9

The first 5 multiples of 9 are

9, 18, 27, 36, 45

iii) 16

The first 5 multiples of 16 are

16, 32, 48, 64, 80

(iv) 11

The first 5 multiples of 11 are

11, 22, 33, 44, 55

(v) 21

The first 5 multiples of 21 are

21, 42, 63, 84, 105

6. Find first three common multiples of the given numbers.

(i) 24, 16

(ii) 12, 9

(iii) 24, 36

i. Multiples of 24 and 16

Multiples of 24 are 24, 48, 72, 96, 120, 144, 168

Multiples of 16 are 16, 32, 48, 64, 80, 96, 112, 128, 144

The common multiples of 24 and 16 are 48, 96, 144

ii. Multiples of 12 and 9

Multiples of 12 are 12, 24, 36, 48, 60, 72, 84, 96, 108, 120

Multiples of 9 are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99, 108, 117

The common multiples of 12 and 9 are 36, 72, 108

iii. Multiples of 24 and 36

Multiples of 24 are 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, 264, 288

Multiples of 36 are 36, 72, 108, 144, 180, 216, 252, 288

The common multiples of 24 and 36 are 144, 288, 432

7. Find L.C.M of the given numbers.

(i) 12 and 28

(ii) 16 and 24

(iii) 8 and 14

(iv) 30 and 20

i) 12 and 28

Multiples of 12 are 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168….

Multiples of 28 are 28, 56, 84, 112, 140,168,196....

Common multiples of 12 and 28 are 84, 168, …

LCM of 12 and 28 is 84

ii) 16 and 24

Multiples of 16 are 16, 32, 48, 64, 80, 96, 112, 128, 144, 160….

Multiples of 24 are 24, 48, 72, 96, 120, 144, ….

Common multiples of 16 and 24 are 48, 96, 144....

LCM of 16 and 24 is 48

iii) 8 and 14

Multiples of 8 are 8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, ….

Multiples of 14 are 14, 28, 42, 56, 70, 84, 98, 112, 126, ....

Common multiples of 8 and 14 are 56, 112, ….

LCM of 8 and 14 is 56

iv) 30 and 20

Multiples of 30 are 30, 60, 90, 120, 150, 180, 210, 240, 270, 360....

Multiples of 20 are 20, 40, 60, 80, 100, 120, 140, 160, 180, 200

Common multiples of 30 and 20 are 60, 120, 180

LCM of 30 and 20 is 60

8. Ramya visits the gym five days once and Kavitha visits the gym six days once. In which day will they meet each other?

Ramya visits the gym 5 days once Kavitha visits the gym, 6 days once

We have to find LCM of 5 and 6

LCM of 5, 6 5 = 1×5

6 = 2×3

LCM of 5, 6 = 2 × 3 × 5 = 30

They both will meet 30th day.

9. Arun and shahjahan goes for walking in a circular path of a park in the same direction. Arun takes 6 minutes to complete one round, while shahjahan takes 8 minutes to complete one round. In how many minutes will they meet each other?

Arun takes 6 minutes to complete one round. Shanjahan minutes to complete one round.

We have to take LCM of 6,8 6= 2 × 3

8= 2×2×2

LCM of 6 and 8 = 2 × 2 × 2 × 3 = 24

They both will meet at 24th minute.

Exercise 2.2

1. i) b.535 ii) b. 26 iii) a. 32 iv) c. 1,2,3,6 v) d. 72

2. i) 1,7 ii) 2 iii) 12 iv) 15 v) 1,5,7

3. i) 1,5,25 ii) 1,2,3,4,6,9,12,18,36 iii) 1,2,7,14 iv) 1,2,4,8,16 v) 1,2,3,4,6,12

4. 5. i) 7, 14, 21, 28, 35 ii) 9, 18, 27, 36, 45 iii) 16, 32, 48, 64, 80 iv) 11, 22, 33, 44, 55 v) 21, 42, 63, 84, 104

6. i) 48, 96, 144 ii) 108, 216, 324 iii) 864, 1728, 2592

7. i) 84 ii) 48 iii) 56 iv) 60

8. 30th day

9. 24 minutes

Tags : Numbers | Term 2 Chapter 2 | 5th Maths , 5th Maths : Term 2 Unit 2 : Numbers
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5th Maths : Term 2 Unit 2 : Numbers : Exercise 2.2 (Least Common Multiple LCM) | Numbers | Term 2 Chapter 2 | 5th Maths