**Playing with Numbers**

**Exercise 3.1**

1). Write all the factors of the following numbers:

a). 24 b). 15 c). 21

d). 27 e). 12 f). 20

g). 18 h). 23 i). 36

Answers:

a). 24

24= 1 X 24 24 = 2 X 12

24 = 3 X 8 24 = 4 X 6

Therefore, factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24.

b). 15

15 = 1 X 15 15 = 3 X 5

Therefore, factors of 15 are 1, 3, 5 and 15.

c). 21

21 = 1 X 21 21 = 3 X 7

Therefore, of 21 are 1, 3, 7 and 21.

d). 27

27 = 1 X 27 27 = 3 X 9

Therefore, factors of 27 are 1, 3, 9 and 27.

e). 12

12 = 1 X 12 12 = 2 X 6

12 = 3X 4

Therefore, factors of 12 are 1, 2, 3, 4, 6 and 12.

f). 20

20 = 1 X 20 20 = 2 X 10

20 = 4 X 5

Therefore, factors of 20 are 1, 2, 4, 5, 10 and 20.

g). 18

18 = 1 X 18 18 = 2 X 9

18 = 3 X 6

Therefore, factors of 18 are 1, 2, 3, 6, 9 and 18.

h). 23

23 = 1 X 23

Therefore, factors of 23 are 1 and 23.

i). 36

36 = 1 X 36 36 = 2 X 18

36 = 3 X 12 36 = 4 X 9

36 = 6 X 6

factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36.

2). Write the first five multiples of :

a). 5 b). 8 c). 9

Answers:

a). 5

The first five multiples of 5 are 5, 10, 15, 20 and 25.

b). 8

The first five multiples of 8 are 8, 16, 24, 32 and 40.

c). 9

The first five multiples of 9 are 9, 18, 27, 36 and 4

3). Match the items in column 1 with the items in column 2.

Column 1 Column 2

i). 35 a). multiple of 8

ii). 15 b). multiple of 7

iii). 16 c). multiple of 70

iv). 20 d). factor of 30

v). 25 e). factor of 50

f). factor of 20

Answers:

i). 35 – multiple of 7

ii). 15 – factor of 30

iii). 16 – multiple of 8

iv). 20 – factor of 20

v). 25 – factor of 50

4). Find all the multiples of 9 upto 100.

Multiples of 9 are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90 and 99.

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Exercise 3.2

Exercise 3.3

Exercise 3.4

Exercise 3.5

Exercise 3.6

Exercise 3.7

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