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