Wednesday, 9 May 2012

CBSE Class 6th ( VI) Mathematics Chapter 8. Decimals: Exercise 8.5

Things to remember

  1. To understand the parts of one whole (i.e. a unit) we represent a unit by a block. One block divided into 10 equal parts means each part is 1/10(one-tenth) of a unit. It can be written as 0.1 in decimal notation. The dot represents the decimal point and it comes between the units place and the tenths place.
  2. Every fraction with denominator 10 can be written in decimal notation and vice-versa.
  3. One block divided into 100 equal parts means each part is ( 1/100 )(one-hundredth) of a unit. It can be written as 0.01 in decimal notation.
  4. Every fraction with denominator 100 can be written in decimal notation and vice-versa.
  5. In the place value table, as we go from left to the right, the multiplying factor becomes 1/10 of the previous factor.
  6. All decimals can also be represented on a number line.
  7. Every decimal can be written as a fraction.
  8. Any two decimal numbers can be compared among themselves. The comparison can start with the whole part. If the whole parts are equal then the tenth parts can be compared and so on.
  9. Decimals are used in many ways in our lives. For example, in representing units of money, length and weight.
1. Find the sum in each of the following :
  1. 0.007 + 8.5 + 30.08
  2. 15 + 0.632 + 13.8
  3. 27.076 + 0.55 + 0.004
  4. 25.65 + 9.005 + 3.7
  5. 0.75 + 10.425 + 2
  6. 280.69 + 25.2 + 38
Answer:
  1. 0.007 + 8.5 + 30.08 = 38.587
  2. 15 + 0.632 + 13.8 = 29.432
  3. 27.076 + 0.55 + 0.004 = 27.63
  4. 25.65 + 9.005 + 3.7 = 38.355
  5. 0.75 + 10.425 + 2 = 13.175
  6. 280.69 + 25.2 + 38 = 343.89
2. Rashid spent Rs 35.75 for Maths book and Rs 32.60 for Science book. Find the total amount spent by Rashid. Answer:
The amount of money, Rashid spent for
Maths book
=Rs. 35.75
The amount of money, Rashid spent for
Science book
=Rs. 32.60
The total amount spent by Rashid = Rs 35.75 + 32.60
=Rs. 68.35
3. Radhika’s mother gave her Rs 10.50 and her father gave her Rs 15.80, find the total amount given to Radhika by the parents. Answer:
The amount of money,mother gave her
Radhika’s
=Rs. 10.50
The amount of money,father gave her
Radhika’s
=Rs. 15.80
The total amount given to Radhika by
the parents
=10.50 + 15.80
=Rs 26.30
4. 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. Answer:
The Nasreen bought cloth for her shirt = 3 m 20 cm
The Nasreen bought cloth for her trouser = 3 m 5cm
The total length of cloth for her
shirt and her trouser bought by her
=3 m 20 cm
+ 3 m 5cm
=5.25 m
5. 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? Answer:
The distance, Naresh walked in the morning = 2 km 35
The distance,Naresh walked in the evening = 1 km 7 m
The distance did he walk morning
and evening in all
= 2 km 35
+ 1 km 7 m
=3.042 km
6. Sunita travelled 15 km 268 m by bus, 7 km 7 m by car and 500 m on foot in order to reach her school. How far is her school from her residence? Answer:
The distance,Sunita travelled by bus=15 km 268 m
The distance,Sunita travelled by car =7 km 7 m
The distance,Sunita travelled
on foot in order to reach
= 500 cm
The total distance, Sunita travelled
from her residence to her school
=15 km 268 m
+ 7 km 7 m
+ 500
=22.775 km
7. Ravi purchased 5 kg 400 g rice, 2 kg 20 g sugar and 10 kg 850g flour. Find the total weight of his purchases. Answer:
The weight of the rice, Ravi purchased =5 kg 400 g
The weight of the sugar, Ravi purchased=2 kg 20 g
The weight of the flour, Ravi purchased=10 kg 850g
The total weight of his purchases =5 kg 400 g
+ 2 kg 20 g
+ 10 kg 850g
=18.270 kg

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