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

__Exercise
1.2__

**1. Add by using grid 0.51 + 0.25**

**Solution: **

Here 0.51 = 51 / 100 and 0.25 = 25 / 100.

First we shade the region 0.51 and then 0.25.

The sum is the total shaded area.

0.51 + 0.25 = 0.76

** **

**2.
Add the following by using place value grid.**

**(i) 25.8 + 18.53**

**Solution: **

25.8 + 18.53.

Using place value grid.

Therefore 25.8 + 18.53 =
44.33

**(ii) 17.4 + 23.435**

**Solution: **

17.4 + 23.435

Lets use the place value grid.

Therefore 17.4 + 23.435 =
40.835

** **

**3. Find the value of 0.46 − 0.13 by grid
model.**

**Solution: **

Here 0.46 = 46 / 100 and 0.13 = 13 / 100

Shading the region 0.46 and then crossing out 0.13 from the
shaded area. The left out shaded region without cross marks is the difference.

So 0.46 – 0.13 = 0.33

** **

**4. Subtract the following by using place
value grid.**

**(i) 6.567 from 9.231**

**Solution: **

Let as use place value grid

Therefore 9.231 – 6.567 =
2.664

**(ii) 3.235 from 7**

**Solution: **

Let as use place value
grid.

Therefore 7 – 3.235 = 3.765

** **

**5. ****Simplify:
23.5 − 27.89 + 35.4 − 17.**

**Solution: **

23.5 – 27.89 + 35.4 – 17 =
14.01

** **

**6. Sulaiman bought 3.350 kg of
Potato, 2.250 kg of Tomato and some Onions. If the weight of the total items
are 10.250 kg, then find the weight of Onions?**

**Solution: **

Weight of Potato = 3.350 kg

Weight of Tomato = 2.250 kg

Total weight of Potato and Tomato = (3.350 + 2.250 kg)

= 5.600 kg

Weight of potato, tomato and onions = 10.250

Weight of potato and tomato = 5.600

∴ Weight of onions = (10.250 – 5.600) kg = 4.650 kg

Weight of onions = 4.650
kg

** **

**7. What should be subtracted from 7.1
to get 0.713?**

**Solution: **

To get the number to be subtracted

We have 7.1–0.713 = 6.387

∴ The number to be subtracted = 6.387

** **

**8. How much is 35.6 km less than
53.7 km?**

**Solution: **

To get the answer we must subtract 53.7km – 35.6 km = 18.1 km

So 35.6 km is 18.1 km less than 53.7 km.

** **

**9. Akilan purchased a geometry box for
₹ 25.75, a pencil for ₹ 3.75 and a pen for ₹ 17.90. He gave ₹ 50 to the shopkeeper.
What amount did he get back?**

**Solution: **

Cost of geometry box = ₹
25.75 (+)

Cost of
Pencil box = ₹ 3.75

Cost
of a pen = __₹ 17.90__

Amount to be
paid = __₹ 47.40__

Amount
paid = ₹ 50.00 (–)

Amount to
be paid = ₹ __47.40__

Amount to
get back = ₹ __2.60__

**∴**** Amount to get back = ₹ 2.60**

** **

**10.
Find the perimeter of an equilateral triangle with a side measuring 3.8 cm.**

**Solution: **

Perimeter of an equilateral triangle = (Side + Side + Side) Sq.
units.

Given side = 3.8

∴ Perimeter = 3.8 + 3.8 + 3.8

Perimeter of the triangle = 11.4 cm

** **

__Objective type questions__

**11.
1.0 + 0.83=?**

(i) 0.17

(ii) 0.71

(iii) 1.83

(iv) 1.38

**Answer: (iii) 1.83**

**12.
7.0 – 2.83 = ? **

(i) 3.47

(ii) 4.17

(iii) 7.34

(iv) 4.73

**Answer: (ii) 4.17**

**13.
Subtract 1.35 from 3.51**

(i) 6.21

(ii) 4.86

(iii) 8.64

(iv) 2.16

Answer: **(iv) 2.16**

**14.
Sum of two decimals is 4.78. If one decimal is 3.21, then the other one is**

(i)1.57

(ii) 1.75

(iii)1.59

(iv) 1.58

Answer: **(i) 1.57**

**15.
The difference of two decimals is 86.58 and one of the decimal is 42.31. Find the
other one**

(i) 128.89

(ii) 128.69

(iii) 128.36

(iv) 128.39

Answer: **(i) 128.89**

__ANSWERS:__

**Exercise 1.2**

1.

Ans 0.76

2. (i)

(ii)

3.

Answer: 0.33

4. (i)

5. 14.01

6. 4.650

7. 6.387

8. 18.1

9. 2.60

10. 11.4 *cm*

**Objective type questions **

11. (iii) 1.83

12. (ii) 4.17

13. (iv) 2.16

14. (i) 1.57

15. (i) 128.89

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 1.2 (Addition and Subtraction of Decimal Numbers) | Questions with Answers, Solution | Number System | Term 3 Chapter 1 | 7th Maths

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