Chapter 3: Decimals Exercise – 3.1
Question: 1
Write each of the following as decimals:
(i) 8/100
Solution:
(i) 8/100
Mark the decimal point two places from right to left
Mark the decimal point one place from right to left
9/10 = 0.9
4/100
Mark the decimal point two places from right to left
4/100
= 0.04
Convert 2/10 and 6/1000 into decimals
2/10
Mark the decimal point one place from right to left
2/10
= 0.2
6/1000
Mark the decimal point three places from right to left
6/1000
= 0.006
23, 0.2, 0.006 are unlike decimals. So we convert them into like decimals.
Question: 2
Convert each of the following into fractions in the lowest form:
(i) 0.04
(ii) 2.34
(iii) 0.342
(iv) 17.38
Solution:
(i) 0.04
= 0.04/1
= 4/100
= 1/25
(ii) 2.34
= 2.34/1
= 234/100
= 117/50
(iii) 0.342
= 0.342/1
= 342/1000
= 171/500
(iv) 17.38
=17.38/1
= 1738/100
= 869/50
Question: 3
Express the following fractions as decimals:
(i) 23/10
Solution:
(i) 23/10
= 23/10
= 2.3
Question: 4
Add the following:
(i) 41.8, 39.24, 5.01 and 62.6
(ii) 18.03, 146.3, 0.829 and 5.324
Solution:
(i) 148.65
(ii) 170.483
Question: 5
Find the value of:
(i) 9.756 - 6.28
(ii) 48.1- 0.37
(iii) 108.032 - 86.8
(iv) 100 - 26.32
Solution:
(i) 3.476
(ii) 47.73
(iii) 21.232
(iv) 73.68
Question: 6
Take out 3.547 from 7.2
Solution:
3.653
Question: 7
What is to be added to 36.85 to get 59.41?
Solution:
x + 36.85 = 59.41
x = 59.41-36.85
x = 22.56
Therefore 22.56 is added to 36.85 to get 59.41
Question: 8
What is to be subtracted from 17.1 to get 2.051?
Solution:
17.1- x = 2.051
17.1 = x + 2.051
x = 17.1 - 2.051
x = 15.049
Therefore 15.049 is subtracted from 17.1 to get 15.049
Question: 9
By how much should 34.79 be increased to get 70.15?
Solution:
34.79 + x = 70.15
x = 70.15 - 34.79
x = 35.36
Therefore 35.36 is increased to 70.15
Question: 10
By how much should 59.71 be decreased to get 34.58?
Solution:
59.71 – x = 34.58
59.71 - 34.58 = x
x = 25.13
Therefore 25.13 is decreased to get 34.58