NCERT Solutions: Decimals

# NCERT Solutions for Class 8 Maths Chapter 8 - Decimals

## Exercise 8.1

Q1. Which is greater:
(a) 0.3 or 0.4
(b) 0.07 or 0.02
(c) 3 or 0.8
(d) 0.5 or 0.05
(e) 1.23 or 1.2
(f) 0.099 or 0.19
(g) 1.5 or 1.50
(h) 1.431 or 1.490
(i) 3.3 or 3.300
(j) 5.64 or 5.603
Ans: (a) 0.3 or 0.4
Whole parts for both the numbers are same. We know that the tenth part of 0.4 is greater than that of
0.3
∴ 0.4 > 0.3

(b) 0.07 or 0.02
Both the numbers have same parts up to the tenth place but the hundredth part of 0.07 is greater than that of 0.02
∴ 0.07 > 0.02

(c) 3 or 0.8
The whole part of 3 is greater than that of 0.8
∴ 3 > 0.8

(d) 0.5 or 0.05
Whole parts for both the numbers are same. Here the tenth part of 0.5 is greater than that of 0.05
∴ 0.5 > 0.05

(e) 1.23 or 1.20
Here both the numbers have same parts up to the tenth place. The hundredth part of 1.23 is greater than that of 1.20
∴ 1.23 > 1.20

(f) 0.099 or 0.19
Whole parts for both the numbers are same. Here the tenth part of 0.19 is greater than that of 0.099
∴ 0.099 < 0.19

(g) 1.5 or 1.50
We may find that both numbers have same parts up to the tenth place. Here 1.5 have no digit at hundredth place. It represents that this digit is 0, which is equal to the digit at hundredth place of 1.50.
∴ Both these numbers are equal

(h) 1.431 or 1.490
Here, both the numbers have same parts up to the tenth place but the hundredth part of 1.490 is greater than that of 1.431
∴ 1.431 < 1.490

(i) 3.3 or 3.300
Here, both numbers have same parts up to the tenth place. There are no digits at hundredth and thousandth place of 3.3. It represents that these numbers are 0, which is equal to the digits at hundredth and thousandth place of 3.300.
∴ Both these numbers are equal

(j) 5.64 or 5.603
Here both numbers have same parts up to the tenth place but the hundredth part of 5.64 is greater than that of 5.603
∴ 5.64 > 5.603

Q2. Make five more examples and find the greater:
(a) 1.8 or 1.82
(b) 1.0009 or 1.09
(c) 10.01 or 100.1
(d) 5.100 or 5.0100
(e) 04.213 or 0421.3
Ans: (a) 32.55 or 32.5
Whole parts for both the numbers are same. The tenth part are also equal, but the hundredth part of 32.55 is greater than that of 32.5
Hence, 32.55 > 32.5

(b) 1 or 0.99
The whole part of 1 is greater than that of 0.99
∴ 1 > 0.99

(c) 1.09 or 1.093
Here both the numbers have same parts up to the hundredth. But the thousandth part of 1.093 is greater than that of 1.09
∴ 1.093 > 1.09

(d) 2 or 1.99
The whole part of 2 is greater than that of 1.99
∴ 2 > 1.99

(e) 2.08 or 2.085
Here both the numbers have same parts up to the hundredth. But the thousandth part of 2.085 is greater than that of 2.08
∴ 2.085 > 2.08

## Exercise 8.2

Q1. Express as rupees using decimals:
(a) 5 paise
(b) 75 paise
(c) 20 paise
(d) 50 rupees 90 paise
(e) 725 paise
Ans: We know that there are 100 paise in 1 rupees
(a) 5 paise = 5 / 100 rupees
= Rupess 0.05

(b) 75 paise = 75 / 100 rupees
= Rupees 0.75

(c) 20 paise = 20 / 100 rupees
= Rupees 0.20

(d) 50 rupees 90 paise = [(50 + 90 / 100)] rupees
= Rupees 50.90

(e) 725 paise = 725 / 100 rupees
= Rupees 7.25

Q2. Express as meters using decimals:
(a) 15 cm
(b) 6 cm
(c) 2 m 45 cm
(d) 9 m 7 cm
(e) 419 cm
Ans: We know that there are 100 cm in 1 metre
(a) 15 cm = 15 / 100 m
= 0.15 m

(b) 6 cm = 6 / 100 m
= 0.06 m

(c) 2 m 45 cm = [(2 + 45 / 100)] m
= 2.45 m

(d) 9 m 7 cm = [(9 + 7 / 100)] m
= 9.07 m

(e) 419 cm = 419 / 100 m
= 4.19 m

Q3. Express as cm using decimals:
(a) 5 mm
(b) 60 mm
(c) 164 mm
(d) 9 cm 8 mm
(e) 93 mm
Ans: We know that there are 10 mm in 1 cm
(a) 5 mm = 5 / 10 cm
= 0.5 cm

(b) 60 mm = 60 / 10 cm
= 6.0 cm

(c) 164 mm = 164 / 10 cm
= 16.4 cm

(d) 9 cm 8 mm = [(9 + 8 / 10)] cm
= 9.8 cm

(e) 93 mm = 93 / 10 cm
= 9.3 cm

Q4. Express as km using decimals:
(a) 8 m
(b) 88 m
(c) 8888 m
(d) 70 km 5 m
Ans: We know that there are 1000 metres in 1 km
(a) 8 m = 8 / 1000 km
= 0.008 km

(b) 88 m = 88 / 1000 km
= 0.088 km

(c) 8888 m = 8888 / 1000 km
= 8.888 km

(d) 70 km 5 m = [(70 + 5 / 1000)] km
= 70.005 km

Q5. Express as kg using decimals:
(a) 2 g
(b) 100 g
(c) 3750 g
(d) 5 kg 8 g
(e) 26 kg 50 g
Ans: We know that there are 1000 grams in 1 kg
(a) 2 g = 2 / 1000 kg
= 0.002 kg

(b) 100 g = 100 / 1000 kg
= 0.1 kg

(c) 3750 g = 3750 / 1000 kg
= 3.750 kg

(d) 5 kg 8 g = [(5 + 8 / 1000)] kg
= 5.008 kg

(e) 26 kg 50 g = [(26 + 50 / 1000)] kg
= 26.050 kg

## Exercise 8.3

Q1. Find the sum in each of the following:
(a) 0.007 + 8.5 + 30.08
(b) 15 + 0.632 + 13.8
(c) 27.076 + 0.55 + 0.004
(d) 25.65 + 9.005 + 3.7
(e) 0.75 + 10.425 + 2
(f) 280.69 + 25.2 + 38
Ans:

Q2. Rashid spent Rs 35.75 for Maths book and Rs 32.60 for Science book. Find the total amount spent by Rashid.
Ans: Money spent for Maths book = Rs 35.75
Money spent for Science book = Rs 32.60
Total money spent = Rs 35.75 + Rs 32.60 = Rs 68.35
Therefore, total money spent by Rashid is Rs 68.35.

Q3. Radhika’s mother have her Rs10.50 and her father gave her Rs15.80. Find the total amount given to Radhika by the parents.
Ans: Money given by mother = Rs 10.50
Money given by father = Rs 15.80
Total money received by Radha = Rs 10.50 + Rs 15.80 = Rs 26.30
Therefore, the total money received by Radha is Rs 26.30.

Q4. Nasreen bought 3 m 20 cm cloth for her shirt and 2 m 5 cm cloth for her trouser. Find the total length of cloth bought by her.
Ans: Cloth bought for shirt = 3 m 20 cm = 3.20 m
Cloth bought for trouser = 2 m 5 cm = 2.05 m
Total length of cloth bought by Nasreen = 3.20 + 2.05 = 5.25 m
Therefore, the total length of cloth bought by Nasreen is 5.25 m

Q5. Naresh walked 2 km 35 m in the morning and 1 km 7 m in the evening. How much distance did he walk in all?
Ans: Distance travelled in morning = 2 km 35 m = 2.035 km
Distance travelled in evening = 1 km 7 m = 1.007 km
Total distance travelled = 2.035 + 1.007 = 3.042 km
Therefore, the total distance travelled by Naresh is 3.042 km.

Q6. Sunita travelled 15 km 268 m by bus, 7 km 7 m by car and 500 m by foot in order to reach her school. How far is her school from her residence?
Ans: Distance travelled by bus = 15 km 268 m = 15.268 km
Distance travelled by car = 7 km 7 m = 7.007 km
Distance travelled on foot = 500 m = 0.500 km
Total distance travelled = 15.268 + 7.007 + 0.500 = 22.775 km
Therefore, total distance travelled by Sunita is 22.775 km.

Q7. Ravi purchases 5 kg 400 g rice, 2 kg 20 g sugar and 10 kg 850 g flour. Find the total weight of his purchases.
Ans: Weight of Rice = 5 kg 400 g = 5.400 kg
Weight of Sugar = 2 kg 20 g = 2.020 kg
Weight of Flour = 10 kg 850 g = 10.850 kg
Total weight = 5.400 + 2.020 + 10.850 = 18.270 kg
Therefore, the total weight of Ravi’s purchase = 18.270 kg.

### Exercise 8.4

Q1. Subtract:

(a) Rs. 18.25 from Rs. 20.75

(b) 202.54 m from 250

(c) Rs. 5.36 from Rs. 8.40

(d) 2.051 km from 5.206 km

(e) 0.314 kg from 2.107 kg

Ans:

Q2. Find the value of:
(a) 9.756 – 6.28
(b) 21.05 – 15.27
(c) 18.5 – 6.79
(d) 11.6 – 9.847
Ans:

Q3. Raju bought a book of Rs 35.65. He gave Rs 50 to the shopkeeper. How much money did he get back from the shopkeeper?
Ans: Total amount given to shopkeeper = Rs50
Cost of book = Rs35.65
Amount left = Rs50.00 – Rs35.65
= Rs 14.35
Therefore, Raju got back Rs14.35 from the shopkeeper.

Q4. Rani had Rs18.50. She bought one ice-cream for Rs11.75. How much money does she have now
Ans: Total money = Rs18.50
Cost of Ice-cream = Rs11.75
Amount left = Rs18.50 – Rs11.75
= Rs6.75
Therefore, Rani has Rs6.75 now.

Q5. Tina had 20 m 5 cm long cloth. She cuts 4 m 50 cm length of cloth from this for making a curtain. How much cloth is left with her?
Ans: Total length of cloth = 20 m 5 cm = 20.05 m
Length of cloth used = 4 m 50 cm = 4.50 m
Remaining cloth = 20.05 m – 4.50 m = 15.55 m
Therefore, 15.55 m of cloth is left with Tina.

Q6. Namita travels 20 km 50 m every day. Out of this she travels 10 km 200 m by bus and the rest by auto. How much distance does she travel by auto?
Ans: Total distance travel = 20 km 50 m = 20.050 km
Distance travelled by bus = 10 km 200 m = 10.200 km
Distance travelled by auto = 20.050 – 10.200 = 9.850 km
Therefore, 9.850 km distance travels by auto.

Q7. Aakash bought vegetables weighing 10 kg. Out of this 3 kg 500 g in onions, 2 kg 75 g is tomatoes and the rest is potatoes. What is the weight of the potatoes?
Ans: Weight of onions = 3 kg 500 g = 3.500 kg
Weight of tomatoes = 2 kg 75 g = 2.075 kg
Total weight of onions and tomatoes = 3.500 + 2.075 = 5.575 kg
Therefore, weight of potatoes = 10.000 – 5.575 = 4.425 kg
Thus, the weight of potatoes is 4.425 kg

The document NCERT Solutions for Class 8 Maths Chapter 8 - Decimals is a part of the Class 6 Course Mathematics (Maths) Class 6.
All you need of Class 6 at this link: Class 6

## Mathematics (Maths) Class 6

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## FAQs on NCERT Solutions for Class 8 Maths Chapter 8 - Decimals

 1. What is a decimal number?
Ans. A decimal number is a number that includes a decimal point, which separates the whole number part from the fractional part. It is based on the powers of 10 and can represent both positive and negative numbers.
 2. How do you compare decimal numbers?
Ans. To compare decimal numbers, start by comparing the whole number parts. If they are equal, then compare the tenths place, followed by the hundredths place, and so on. If one decimal has a digit in a place where the other decimal does not, the decimal with the digit is greater.
 3. How do you add and subtract decimal numbers?
Ans. To add or subtract decimal numbers, align the decimal points and then perform the addition or subtraction as usual. If the decimal places are not equal, add zeros to the shorter decimal number to make them equal before performing the operation.
 4. How do you multiply decimal numbers?
Ans. To multiply decimal numbers, multiply them as if they were whole numbers, ignoring the decimal point. Count the total number of decimal places in both numbers, and place the decimal point in the product by counting that many places from the right.
 5. How do you divide decimal numbers?
Ans. To divide decimal numbers, ignore the decimal points and divide the numbers as if they were whole numbers. Count the total number of decimal places in both numbers, and place the decimal point in the quotient by counting that many places from the right.

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