Selina Solutions Concise Maths Class 7 Chapter 4: Decimal Fractions (Decimals) Exercise 4C

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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Access other exercises of Selina Solutions Concise Maths Class 7 Chapter 4: Decimal Fractions (Decimals)

Exercise 4A Solutions

Exercise 4B Solutions

Exercise 4D Solutions

Exercise 4E Solutions

Exercise 4F Solutions

Access Selina Solutions Concise Maths Class 7 Chapter 4: Decimal Fractions (Decimals) Exercise 4C

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 50

(v) 16.32 by 28
It can be written as

16.32 × 28 = 456.96

Selina Solutions Concise Maths Class 7 Chapter 4 Image 51

(vi) 5.037 by 8
It can be written as

5.037 × 8 = 40.296

Selina Solutions Concise Maths Class 7 Chapter 4 Image 52

(vi) 4.6 by 2.1
It can be written as

4.6 × 2.1 = 9.66

Selina Solutions Concise Maths Class 7 Chapter 4 Image 53

(viii) 0.568 by 6.4

It can be written as

0.568 × 6.4 = 3.6352

Selina Solutions Concise Maths Class 7 Chapter 4 Image 54

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 55

(ii) 0.894 x 87
We know that

0.894 x 87 = 77.778

Selina Solutions Concise Maths Class 7 Chapter 4 Image 56

(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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 57

(v) 4.75 x 0.08 x 3
It can be written as

= 4.75 x 0.24

= 1.1400

= 1.14

Selina Solutions Concise Maths Class 7 Chapter 4 Image 58

(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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 59

(vii) 0.8 x 1.2 x 0.25
It can be written as

= 0.96 x 0.25
= 0.2400

= 0.24

Selina Solutions Concise Maths Class 7 Chapter 4 Image 60

(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



Selina Solutions Concise Maths Class 7 Chapter 4 Image 61

(vii) 4.32 by 1.2
It can be written as

4.32 ÷ 1.2

Multiplying by 100

432 ÷ 120 = 3.6

Selina Solutions Concise Maths Class 7 Chapter 4 Image 62

(viii) 7.644 by 1.4
It can be written as

7.644 ÷ 1.4

Multiplying by 1000

7644 ÷ 1400 = 5.46

Selina Solutions Concise Maths Class 7 Chapter 4 Image 63

(ix) 4.8432 by 0.08

It can be written as

4.8432 ÷ 0.08

So we get

48432 ÷ 800 = 60.54

Selina Solutions Concise Maths Class 7 Chapter 4 Image 64

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 65

(ii) 4.4064 ÷ 4
We get

4.4064 ÷ 4 = 1.016

(iii) 27.69 ÷ 30
We get

27.69 ÷ 30 = 0.923

Selina Solutions Concise Maths Class 7 Chapter 4 Image 66

(iv) 19.25 ÷ 25
We get

19.25 ÷ 25 = 0.77

Selina Solutions Concise Maths Class 7 Chapter 4 Image 67

(v) 20.64 ÷ 16
We get

20.64 ÷ 16 = 1.29

Selina Solutions Concise Maths Class 7 Chapter 4 Image 68

(vi) 3.204 ÷ 9
We get

3.204 ÷ 9 = 0.356

Selina Solutions Concise Maths Class 7 Chapter 4 Image 69

(vii) 0.125 ÷ 25
We get

0.125 ÷ 25 = 0.005

Selina Solutions Concise Maths Class 7 Chapter 4 Image 70

(viii) 0.14616 ÷ 72
We get

0.14616 ÷ 72 = 0.00203

Selina Solutions Concise Maths Class 7 Chapter 4 Image 71

(ix) 0.6227 ÷ 1300
We get

0.6227 ÷ 1300 = 0.000479

Selina Solutions Concise Maths Class 7 Chapter 4 Image 72

(x) 257.894 ÷ 0.169
Multiplying by 1000

257894 ÷ 169 = 1526

Selina Solutions Concise Maths Class 7 Chapter 4 Image 73

(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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 74

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 75

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 76

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 77

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 78

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 79

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 80

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 81

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)3 x 5

(vi) (0.2)3 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)3 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)3 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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 82

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

Selina Solutions Concise Maths Class 7 Chapter 4 Image 83

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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