Selina Solutions Concise Maths Class 7 Chapter 4 Decimal Fractions (Decimals) Exercise 4C provides students with the basic knowledge of multiplication and division of decimal numbers. Students can solve the problems on a regular basis and clear their doubts by referring to the solutions PDF. The solutions are strictly according to the current syllabus and marks weightage in the annual exam. Students can boost their confidence in solving tricky problems with the help of solutions PDF. Selina Solutions Concise Maths Class 7 Chapter 4 Decimal Fractions (Decimals) Exercise 4C, PDF links are provided here.
Selina Solutions Concise Maths Class 7 Chapter 4: Decimal Fractions (Decimals) Exercise 4C Download PDF
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1. Multiply:
(i) 0.87 by 10
(ii) 2.948 by 100
(iii) 6.4 by 1000
(iv) 5.8 by 4
(v) 16.32 by 28
(vi) 5. 037 by 8
(vi) 4.6 by 2.1
(viii) 0.568 by 6.4
Solution:
(i) 0.87 by 10
It can be written as
0.87 × 10 = 8.7
(ii) 2.948 by 100
It can be written as
2.948 × 100 = 294.8
(iii) 6.4 by 1000
It can be written as
6.4 × 1000 = 6400
(iv) 5.8 by 4
It can be written as
5.8 × 4 = 23.2
(v) 16.32 by 28
It can be written as
16.32 × 28 = 456.96
(vi) 5.037 by 8
It can be written as
5.037 × 8 = 40.296
(vi) 4.6 by 2.1
It can be written as
4.6 × 2.1 = 9.66
(viii) 0.568 by 6.4
It can be written as
0.568 × 6.4 = 3.6352
2. Multiply each number by 10, 100, 1000:
(i) 0.5
(ii) 0.112
(iii) 4.8
(iv) 0.0359
(v) 16.27
(vi) 234.8
Solution:
(i) 0.5
It can be written as
0.5 × 10 = 5
0.5 × 100 = 50
0.5 × 1000 = 500
(ii) 0.112
It can be written as
0.112 × 10 = 1.12
0.112 × 100 = 11.2
0.112 × 1000 = 112
(iii) 4.8
It can be written as
4.8 × 10 = 48
4.8 × 100 = 480
4.8 × 1000 = 4800
(iv) 0.0359
It can be written as
0.0359 × 10 = 0.359
0.0359 × 100 = 3.59
0.0359 × 1000 = 35.9
(v) 16.27
It can be written as
16.27 × 10 = 162.7
16.27 × 100 = 1627
16.27 × 1000 = 16270
(vi) 234.8
It can be written as
234.8 × 10 = 2348
234.8 × 100 = 23480
234.8 × 1000 = 234800
3. Evaluate:
(i) 5.897 x 2.3
(ii) 0.894 x 87
(iii) 0.01 x 0.001
(iv) 0.84 x 2.2 x 4
(v) 4.75 x 0.08 x 3
(vi) 2.4 x 3.5 x 4.8
(vii) 0.8 x 1.2 x 0.25
(viii) 0.3 x 0.03 x 0.003
Solution:
(i) 5.897 x 2.3
We know that
5.897 x 2.3 = 13.5631
(ii) 0.894 x 87
We know that
0.894 x 87 = 77.778
(iii) 0.01 x 0.001
We know that
0.01 x 0.001 = 0.00001
(iv) 0.84 x 2.2 x 4
It can be written as
= 0.84 x 8.8
= 7.392
(v) 4.75 x 0.08 x 3
It can be written as
= 4.75 x 0.24
= 1.1400
= 1.14
(vi) 2.4 x 3.5 x 4.8
It can be written as
= 8.40 x 4.8
= 8.4 x 4.8
We get
= 40.32
(vii) 0.8 x 1.2 x 0.25
It can be written as
= 0.96 x 0.25
= 0.2400
= 0.24
(viii) 0.3 x 0.03 x 0.003
It can be written as
= 0.009 x 0.003
= 0.000027
4. Divide:
(i) 54.9 by 10
(ii) 7.8 by 100
(iii) 324.76 by 1000
(iv) 12.8 by 4
(v) 27.918 by 9
(vi) 4.672 by 8
(vii) 4.32 by 1.2
(viii) 7.644 by 1.4
(ix) 4.8432 by 0.08
Solution:
(i) 54.9 by 10
It can be written as
54.9 ÷ 10 = 5.49
(ii) 7.8 by 100
It can be written as
7.8 ÷ 100 = 0.078
(iii) 324.76 by 1000
It can be written as
324.76 ÷ 1000 = 0.32476
(iv) 12.8 by 4
It can be written as
12.8 ÷ 4 = 3.2
(v) 27.918 by 9
It can be written as
27.918 ÷ 9 = 3.102
(vi) 4.672 by 8
It can be written as
4.672 ÷ 8 = 0.584
(vii) 4.32 by 1.2
It can be written as
4.32 ÷ 1.2
Multiplying by 100
432 ÷ 120 = 3.6
(viii) 7.644 by 1.4
It can be written as
7.644 ÷ 1.4
Multiplying by 1000
7644 ÷ 1400 = 5.46
(ix) 4.8432 by 0.08
It can be written as
4.8432 ÷ 0.08
So we get
48432 ÷ 800 = 60.54
5. Divide each of the given numbers by 10, 100, 1000 and 10000
(i) 2.1
(ii) 8.64
(iii) 5-01
(iv) 0.0906
(v) 0.125
(vi) 111.11
Solution:
(i) 2.1
It can be written as
2.1 ÷ 10 = 0.21
2.1 ÷ 100 = 0.021
2.1 ÷ 1000 = 0.0021
2.1 ÷ 10000 = 0.00021
(ii) 8.64
It can be written as
8.64 ÷ 10 = 0.864
8.64 ÷ 100 = 0.0864
8.64 ÷ 1000 = 0.00864
8.64 ÷ 10000 = 0.000864
(iii) 5.01
It can be written as
5.01 ÷ 10 = 0.501
5.01 ÷ 100 = 0.0501
5.01 ÷ 1000 = 0.00501
5.01 ÷ 10000 = 0.000501
(iv) 0.0906
It can be written as
0.0906 ÷ 10 = 0.00906
0.0906 ÷ 100 = 0.000906
0.0906 ÷ 1000 = 0.0000906
0.0906 ÷ 10000 = 0.00000906
(v) 0.125
It can be written as
0.125 ÷ 10 = 0.0125
0.125 ÷ 100 = 0.00125
0.125 ÷ 1000 = 0.000125
0.125 ÷ 10000 = 0.0000125
(vi) 111.11
It can be written as
111.11 ÷ 10 = 11.111
111.11 ÷ 100 = 1.1111
111.11 ÷ 1000 = 0.11111
111.11 ÷ 10000 = 0.011111
6. Evaluate :
(i) 9.75 ÷ 5
(ii) 4.4064 ÷ 4
(iii) 27.69 ÷ 30
(iv) 19.25 ÷ 25
(v) 20.64 ÷ 16
(vi) 3.204 ÷ 9
(vii) 0.125 ÷ 25
(viii) 0.14616 ÷ 72
(ix) 0.6227 ÷ 1300
(x) 257.894 ÷ 0.169
(xi) 6.3 ÷ (0.3)²
Solution:
(i) 9.75 ÷ 5
We get
9.75 ÷ 5 = 1.95
(ii) 4.4064 ÷ 4
We get
4.4064 ÷ 4 = 1.016
(iii) 27.69 ÷ 30
We get
27.69 ÷ 30 = 0.923
(iv) 19.25 ÷ 25
We get
19.25 ÷ 25 = 0.77
(v) 20.64 ÷ 16
We get
20.64 ÷ 16 = 1.29
(vi) 3.204 ÷ 9
We get
3.204 ÷ 9 = 0.356
(vii) 0.125 ÷ 25
We get
0.125 ÷ 25 = 0.005
(viii) 0.14616 ÷ 72
We get
0.14616 ÷ 72 = 0.00203
(ix) 0.6227 ÷ 1300
We get
0.6227 ÷ 1300 = 0.000479
(x) 257.894 ÷ 0.169
Multiplying by 1000
257894 ÷ 169 = 1526
(xi) 6.3 ÷ (0.3)²
We can write it as
= 6.3 ÷ (0.3 × 0.3)
By further calculation
= 6.3 ÷ 0.09
Multiply both sides by 100
= 630 ÷ 9 = 70
7. Evaluate:
(i) 4.3 x 0.52 x 0.3
(ii) 3.2 x 2.5 x 0.7
(iii) 0.8 x 1.5 x 0.6
(iv) 0.3 x 0.3 x 0.3
(v) 1.2 x 1.2 x 0.4
(vi) 0.4 x 0.04 x 0.004
(vii) 0.5 x 0.6 x 0.7
(viii) 0.5 x 0.06 x 0.007
Solution:
(i) 4.3 x 0.52 x 0.3
We know that
Here the sum of decimal places = 1 + 2 + 1 = 4
So we get
4.3 x 0.52 x 0.3 = 0.6708
(ii) 3.2 x 2.5 x 0.7
We know that
Here the sum of decimal places = 1 + 1 + 1 = 3
So we get
3.2 x 2.5 x 0.7 = 5.600 or 5.6
(iii) 0.8 x 1.5 x 0.6
We know that
Here the sum of decimal places = 1 + 1 + 1 = 3
So we get
0.8 x 1.5 x 0.6 = 0.720 or 0.72
(iv) 0.3 x 0.3 x 0.3
We know that
Here the sum of decimal places = 1 + 1 + 1 = 3
So we get
0.3 x 0.3 x 0.3 = 0.027
(v) 1.2 x 1.2 x 0.4
We know that
Here the sum of decimal places = 1 + 1 + 1 = 3
So we get
1.2 x 1.2 x 0.4 = 0.576
(vi) 0.4 x 0.04 x 0.004
We know that
Here the sum of decimal places = 1 + 2 + 3 = 6
So we get
0.4 x 0.04 x 0.004 = 0.000064
(vii) 0.5 x 0.6 x 0.7
We know that
Here the sum of decimal places = 1 + 1 + 1 = 3
So we get
0.5 x 0.6 x 0.7 = 0.210 or 0.21
(viii) 0.5 x 0.06 x 0.007
We know that
Here the sum of decimal places = 1 + 2 + 3 = 5
So we get
0.5 x 0.06 x 0.007 = 0.00021
8. Evaluate:
(i) (0.9)²
(ii) (0.6)² x 0.5
(iii) 0.3 x (0.5)²
(iv) (0.4)³
(v) (0.2)3Â x 5
(vi) (0.2)3Â x 0.05
Solution:
(i) (0.9)²
It can be written as
0.9 x 0.9 = 0.81
Here the sum of decimal places is 1 + 1 = 2
(ii) (0.6)² x 0.5
It can be written as
= 0.6 x 0.6 x 0.5
On further calculation
= 0.36 x 0.5
= 0.180 or 0.18
Here the sum of decimal places is 1 + 1 + 1 = 3
(iii) 0.3 x (0.5)²
It can be written as
= 0.3 x 0.5 x 0.5
On further calculation
= 0.3 x 0.25
= 0.075
Here the sum of decimal places is 1 + 1 + 1 = 3
(iv) (0.4)³
It can be written as
= 0.4 x 0.4 x 0.4
On further calculation
= 0.16 x 0.4
= 0.064
Here the sum of decimal places is 1 + 1 + 1 = 3
(v) (0.2)3Â x 5
It can be written as
= 0.2 x 0.2 x 0.2 x 5
On further calculation
= 0.008 x 5
= 0.40 or 0.4
Here the sum of decimal places is 1 + 1 + 1 = 3
(vi) (0.2)3Â x 0.05
It can be written as
= 0.2 x 0.2 x 0.2 x 0.05
On further calculation
= 0.008 x 0.05
= 0.00040
Here the sum of decimal places is 1 + 1 + 1 + 1 + 1 = 5
9. Find the cost of 36.75 kg wheat at the rate of ₹12.80 per kg.
Solution:
It is given that
Weight of wheat = 36.75 kg
Cost of wheat per kg = ₹12.80
So the cost of 36.75 kg wheat = 36.75 x 12.80 = ₹470.40
10. The cost of a pen is ₹56.15. Find the cost of 16 such pens.
Solution:
It is given that
Cost of a pen = ₹56.15
So the cost of 16 such pens = 16 x 56.15 = ₹898.40
11. Evaluate:
(i) 0.0072 ÷ 0.06
(ii) 0.621 ÷ 0.3
(iii) 0.0532 ÷ 0.005
(iv) 0.01162 ÷ 0.14
(v) (7.5 x 40.4) ÷ 25
(vi) 2.1 ÷ (0.1 x 0.1)
Solution:
(i) 0.0072 ÷ 0.06
Multiplying both numerator and denominator by 100
= (0.0072 x 100)/ (0.06 x 100)
On further calculation
= 0.72/6
= 0.12
(ii) 0.621 ÷ 0.3
Multiplying both numerator and denominator by 10
= (0.621 x 10)/ (0.3 x 10)
On further calculation
= 6.21/3
= 2.07
(iii) 0.0532 ÷ 0.005
Multiplying both numerator and denominator by 1000
= (0.0532 x 1000)/ (0.005 x 1000)
On further calculation
= 53.2/5
= 10.64
(iv) 0.01162 ÷ 0.14
Multiplying both numerator and denominator by 100
= (0.01162 x 100)/ (0.14 x 100)
On further calculation
= 1.162/14
= 0.083
(v) (7.5 x 40.4) ÷ 25
It can be written as
= 303/25
= 12.12
(vi) 2.1 ÷ (0.1 x 0.1)
Multiplying both numerator and denominator by 100
= (2.1 x 100)/ (0.01 x 100)
On further calculation
= 210/1
= 210
12. Fifteen identical articles weigh 31.50 kg. Find the weight of each article.
Solution:
It is given that
Total weight of 15 identical articles = 31.50 kg
So the weight of each article = 31.50 – 15 = 2.1 kg
Hence, the weight of each article is 2.1 kg.
13. The product of two numbers is 211.2. If one of these two numbers is 16.5, find the other number.
Solution:
It is given that
Product of two numbers = 211.2
One of the two numbers = 16.5
So the other number = 211.2 ÷ 16.5
On further calculation
= (211.2 x 10)/ (16.5 x 10)
So we get
= 2112/165
= 12.8
14. One dozen identical articles cost ₹45.96. Find the cost of each article.
Solution:
It is given that
Cost of one dozen articles = ₹45.96
We know that one dozen = 12
So the cost of one article = 45.96 ÷ 12 = ₹3.83
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