Chapter 7: Decimals – Exercise 7.6
Question: 1
Express as rupees (Rs) using decimals
i) 15 paisa
ii) 5 paisa
iii) 350 paisa
iv) 2 rupees 60 paisa
Solution:
i) We know that 100 paisa = Rs. 1
Therefore, 1 paisa = Rs. 1/100
15 paisa = 15/100
= Rs 0.15
ii) We know that 100 paisa = Rs. 1
Therefore, 1 paisa = Rs. 1/100
5 paisa = 5/100
= Rs 0.05
iii) We know that 100 paisa = Rs. 1
Therefore, 1 paisa = Rs. 1/100
35 paisa = 350/100
= Rs 3.50
iv) We know that 100 paisa = Rs. 1
Therefore, 1 paisa = Rs. 1/100
2 rupees 60 paisa = 2 + 60100
= Rs 2.60
Question: 2
Express as metres (m) using decimals
i) 15 cm
ii) 8 cm
iii) 135 cm
iv) 3 m 65 cm
Solution:
i) We know that 100 cm = 1m
Therefore 1 cm = 1/100 m
0.15 m
ii) We know that 100 cm = 1m
Therefore 1 cm = 1/100 m
= 0.08 m
iii) We know that 100 cm = 1m
Therefore 1 cm = 1/100 m
= 1.35 m
iv) We know that 100 cm = 1m
Therefore 1 cm = 1/100 m
= 3.65 m
Question: 3
Express as centimetre (cm) using decimals
i) 5 mm
ii) 60 mm
iii) 175 mm
iv) 4 cm 5 mm
Solution:
i) We know that 10 mm = 1cm
Therefore 1 mm = 1/10 cm
5 mm = 5/10 cm
= 0.5 cm
ii) We know that 10 mm = 1cm
Therefore 1 mm = 1/10 cm
60 mm = 60/10 cm
= 6 cm
iii) We know that 10 mm = 1cm
Therefore 1 mm = 1/10 cm
175 mm = 175/10 cm
= 17.5 cm
iv) We know that 10 mm = 1cm
Therefore 1 mm = 1/10 cm
4 cm 5 mm = 4 + 5/10
= 4.5 cm
Question: 4
Express as kilogram (km) using decimals
i) 5 m
ii) 55 m
iii) 555 m
iv) 5555 m
v) 15 km 35 m
Solution:
i) We know that 1000 m = 1 km
Therefore 1m = 1/1000 km
5 m = 5/1000 km
= 0.005 km
ii) We know that 1000 m = 1 km
Therefore 1m = 1/1000 km
55 m = 55/1000 km
= 0.055 km
iii) We know that 1000 m = 1 km
Therefore 1m = 1/1000 km
555 m = 555/1000 km
= 0.555 km
iv) We know that 1000 m = 1 km
Therefore 1m = 1/1000 km
5m = 5/1000 km
= 5.555 km
v) We know that 1000 m = 1 km
Therefore 1m = 1/1000 km
15 km 35 m = 15 + 351000
= 15.035 km
Question: 5
Express each of the following without using decimals
i) 8g
ii) 150 g
iii) 2750 g
iv) 5 kg 750 g
v) 36 kg 50 g
Solution:
i) We know that 1000g = 1kg
Therefore 1 g = 1/1000 kg = 0.001 kg
8g = 8/1000 kg
= 0.008 kg
ii) We know that 1000 g = 1kg
Therefore 1g = 1/1000 kg = 0.001 kg
150 g = 150/1000 kg
= 0.150 kg
iii) We know that 1000 g = 1kg
Therefore 1 g = 1/1000 kg = 0.001 kg
2750g = 2750/1000 kg
= 2.750 kg
iv) We know that 1000 g = 1kg
Therefore 1 g = 1/1000 kg = 0.001 kg
5 kg 750 g = 5 + 7501000
= 5.750 kg
v) We know that 1000 g = 1kg
Therefore 1g =1/1000 kg = 0.001 kg
36 kg 50 g = 36 + 501000
= 36.050 kg
Question: 6
Express each of the following without using decimals
i) Rs.5.25
ii) 8.354 kg
iii) 3.05 km
iv) 7.54 m
v) 15.005 kg
vi) 12.05 m
Solution:
i) We know 100 paisa = 1 rupee
So, 1 paisa = 1/100 rupee
Therefore, Rs 5.25 = 5 + 0.25
= 5 + 25100 = Rs 5 and 25 paisa
ii) We know that 100g = 1kg
So 1 g = 1/1000 kg
Therefore, 8.354 = 8 + 0.354 = 8 + 3541000 = 8 kg 354 g
1. 3.5 cm
We know that 10 mm = 1cm
So, 1 mm = 1/10 cm
Therefore 3.5 = 3 + 0.5
= 3 + 510 = 3 cm 5 mm
iii) We know that 1000 m = 1 km
Therefore 3.05 = 3 + 0.05
= 3 km 50 m
iv) We know that 100 cm = 1m
Therefore 7.54 = 7 + 0.54
= 7m 54 cm
v) We know that 1 kg = 1000 g
Therefore, 15.005 = 15 + 0.005
= 15 kg 5 g
vi) We know that 1m = 100 cm
Therefore 12.05 = 12 + 0.05
= 12 m 5 cm