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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