Page 29 - SM inner class 7.cdr

Converting Lower Units to Higher Units Converting Higher Units to Lower Units

To change a lower unit to a higher unit of measure, we To change from higher units to lower units, we
convert the lower unit into a decimal fraction first and always multiply the higher unit by the difference
then change it into a decimal number to express in the between the two units.
higher unit like this.

Example11 : Con vert 3921 m in km Example14 : Con vert 1.358 kg to g
3921 1358 1000 1358 g
´
=
.
= (since 1000 m =1 km) = 3921. km
1000
Example12 : Con vert 568 g in kg. Example15 : Con vert 2.506 km to m
568 2506 1000 = 2506 m
.
´
= (since 1000 g = 1 kg) = 0.568 kg
1000
Example13 : Con vert 3105 l in kl. Example16 : Con vert 8521. kl to l
3105 8521 1000 = 8521 l
.
´
= (since 1000 l = 1 kl) = 3.105 kl
1000

Ex am ple 17. Con vert 125 metres into ki lo me ters. Terminating and Non-terminating
125 Decimals
So lu tion : 125 metres = kilo metres
1000 In the decimal representations such as 0.12,
0.25 + 0.125, etc. we have found that the
= .125 kilometres
decimal numbers are ending with a finite
Ex am ple 18. Con vert 1.33 metres into number of digits in the decimal part and the
milli metres. long division in such cases always comes to an
end after some finite steps. Such numbers are
So lu tion : 1.33 metres =133 1000. ´ milli metres
known as ter mi nat ing dec i mals.
=1330 millimetres
But in certain cases, it is not possible to
Ex am ple 19. Con vert 1.45 ki lo grams into grams. complete the long division even, if we put
many zeroes in the decimal part.
So lu tion : 1.45 ki lo grams = 1.45 ´1000 grams
For ex am ple : Let us have the decimal
=1450 grams 1 1
rep re sen ta tion of (i) and (ii) .
Ex am ple 20. Con vert 1.32 kilo metres into 3 6
0.3333 0.16666
centimetres. (i) (ii)
3 1.0000 6 1.00000
So lu tion :1.32 kilometres =132 1000. ´ metres –9 –6
10 40
=1320 metres
–9 36
´
=1320 100 centimetres 10 40
9 36
=132000 centimetres 10 40
–9 36
Ex am ple 21. Convert 1.45 decagrams into
1 40
ki lo grams. 36
.
145 1 4
So lu tion : 1.45 decagrams = ki lo gram (i) In case of it is not possible to complete
10 3
= 0145 ki lo gram the division no matter how many zeroes
.
we put after the decimal point. This may

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Mathematics In Focus - 7