7th Maths : Term 3 Unit 1 : Number System : Multiplication of Decimal Numbers : Text Book Back Exercises Questions with Answers, Solution

__Multiplication of Decimal Numbers__

**Exercise 1.3**

**1.
Find the product of the following **

**(i)
0.5 × 3 **

5 × 3 = 15

∴ 0.5 × 3 = 1.5

**(ii)
3.75 × 6**

375 × 6 = 2250

3.75 × 6 = 22.50

**(iii)
50.2 × 4**

502 × 4 = 2008

50.2 × 4 = 200.8

**(iv)
0.03 × 9 **

3 × 9 = 27

0.03 × 9 = 0.27

**(v)
453.03 × 7 **

45303 × 7 = 317121

453.03 × 7= 3171.21

**(vi)
4 × 0.7**

4 × 7 = 28

4 × 0.7 = 2.8

** **

**2. Find the area of the parallelogram
whose base is 6.8 cm and height is 3.5 cm.**

**Solution: **

Base of the parallelogram *b
*= 6.8 cm

Height of the parallelogram *h*
= 3.5 cm

Area of the parallelogram A = *b* ×* h *sq.units = 6.8 × 3.5 cm^{2}

Area of the parallelogram = 23.80 cm^{2}

** **

**3. Find the area of the rectangle whose
length is 23.7 cm and breadth is 15.2 cm.**

**Solution: **

Length of the rectangle *l*
= 23.7 cm

Breadth of the rectangle *b
*= 15.2 cm

Area of the rectangle A = *l*
× *b* sq.units

= 23.7 × 15.2 cm^{2}

Area of the rectangle = 360.24 cm^{2}

** **

**4.
Multiply the following**

**(i)
2.57 × 10**

**(ii)
0.51 × 10**

**(iii)
125.367 × 100**

**(iv)
34.51 ×100**

**(v)
62.735 × 100**

**(vi)
0.7 × 10**

**(vii)
0.03 × 100**

** (viii) 0.4 ×1000**

** **

**5. A wheel of a baby cycle covers 49.7
cm in one rotation. Find the distance covered in 10 rotations.**

**Solution:**

Length covered in 1
rotation = 49.7 cm

Length covered in 10 rotations = 49.7 × 10 cm = 497 cm

** **

**6.
A picture chart costs ₹ 1.50. Radha wants to buy 20 charts to make an album. How
much does she have to pay?**

**Solution: **

Cost of 1 chart = ₹ 1.50

Cost of 20 charts = ₹ 1.50 × 20 = ₹ 30.00

Cost of 20 charts = ₹ 30

** **

**7.
Find the product of the following.**

**(i)
3.6 × 0.3**

36 × 3 = 108

3.6 × 0.3 = 1.08

**(ii)
52.3 × 0.1 **

523 × 1 = 523

52.3 × 0.1 = 5.23

**(iii)
537.4 × 0.2 **

5374 × 2 = 10748

537.4 × 0.2 = 107.48

**(iv)
0.6 × 0.06**

6 × 6 = 36

0.6 × 0.06 = 0.036

** (v) 62.2 × 0.23 **

622 × 23 = 14306

62.2 × 0.23 = 14.306.

**(vi)
1.02 × 0.05 **

102 × 5 = 510

1.02 × 0.05 = 0.0510

**(vii)
10.05 × 1.05 **

1005 × 105 = 105525

10.05 × 1.05 = 10.5525

**(viii)
101.01 × 0.01 **

10101 × l = 10101

101.01 × 0.01 = 1.0101

**(ix)
100.01 ×1.1 **

10001 × 11 = 110011

100.01 × 1.1 = 110.011

** **

__Objective type questions__

**8.
1.07 × 0.1 ________ **

(i) 1.070

(ii) 0.107

(iii) 10.70

(iv) 11.07

**[Answer: (ii) 0.107]**

** Solution: **107 × 1 =
107

1.07 × 0.1 = 0.107

**9.
2.08 × 10 = ________ **

(i) 20.8

(ii) 208.0

(iii) 0.208

(iv) 280.0

**[Answer: (i) 20.8]**

** Solution: **208 × 10 =
2080

2.08 × 10 = 20.80 = 20.8

**10.
A frog jumps 5.3 cm in one jump. The distance
travelled by the frog in 10 jumps is **

** --------- **

(i) 0.53 *cm*

(ii) 530 *cm*

(iii) 53.0 *cm*

(iv) 53.5 *cm*

**[Answer: (iii) 53.0
cm]**

** Solution: **53 × 10 =
530

5.3 × 10 = 53.0

__ANSWERS:__

**Exercise 1.3 **

1. (i) 1.5 (ii) 22.50
(iii) 200.8 (iv) 0.27 (v) 3171.21 (vi) 2.8

2. 23.80 *sq.cm*

3. 360.24 *sq.cm*

4. (i) 25.7 (ii) 5.1
(iii) 12536.7 (iv) 3451 (v) 6273.5 (vi) 7.0 (vii) 3 (viii) 400

5. 497*cm*

6. ₹ 30

7. (i) 1.08 (ii) 5.23
(iii) 107.48 (iv) 0.036 (v) 14.306 (vi) 0.051 (vii) 10.5525 (viii) 1.0101 (ix)
110.011

**Objective
type questions **

8. (ii) 0.107

9. (i) 20.8

10. (iii) 53.0* cm*

* *

Tags : Questions with Answers, Solution | Number System | Term 3 Chapter 1 | 7th Maths , 7th Maths : Term 3 Unit 1 : Number System

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7th Maths : Term 3 Unit 1 : Number System : Exercise 1.3 (Multiplication of Decimal Numbers) | Questions with Answers, Solution | Number System | Term 3 Chapter 1 | 7th Maths

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