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4. Find the difference.
a. 48 m 20 cm and 56 m 40 cm b. 645 m 47 cm and 68 m 69 cm

c. 98 km 205 m and 59 km 326 m d. 48 km 75 m and 18 km 280 m

5. From a roll of 17 m 16 cm wool, a piece of 8 m 42 cm was cut off. Find
the length of wool left in the roll?

6. During a trip, Saket travelled 18 km 325 m by train, 68 km 218 m by
bus, and 8 km 705 m by car. What was the total distance travelled
by Saket?

7. On a certain day, Anil walked 275 m from his home to the bus stop and from there he
travelled 5 km 548 m by bus. In the evening, he returned home travelling the same
distance. Find the total distance travelled by Anil on that day.

8. The length of the Ming Great Wall of China is measured to be 8851
km 800 m. It is made up of 6259 km 600 m of actual wall, 359
km 700 m of trenches and the rest of natural barriers like hills and
rivers. Find the length of the natural barriers that make up the Ming
Great Wall of China.

MeASurIng MASS (WeIghT)

The base unit to measure mass (weight) is the gram (g). It is the standard unit for
measuring mass. Similar to the units of length, mass can also be measured by other
bigger or smaller units.

The units of mass bigger than the gram The units of mass lower than the gram
are decagram (dag), hectogram (hg) are decigram (dg), centigram (cg)
and kilogram (kg). and milligram (mg).
1 dag = 10 g 1 g = 10 dg

1 hg = 100 g 1 dg = 10 cg
1 kg = 1000 g 1 cg = 10 mg

Conversion of Bigger units of Mass into Smaller units

The conversion of units of mass follows the same rules as the units of length.
To convert a bigger unit into a smaller unit, we multiply.

For example, to convert kilograms into grams, we multiply the number of kilograms
by 1000.
example 1. Convert the following into grams.

a. 2 kg b. 7 kg 245 g c. 72 kg 750 g
Solution. a. 2 kg
We know that 1 kg = 1000 g.
2 kg = (2 × 1000) g = 2000 g

156 Mathematics 4