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example 4. Convert:
a. 6 m 9 dm into dm c. 9 cm 7 mm into mm
Solution. a. 6 m 9 dm into dm
6 m 9 dm = 6 m + 9 dm = (6 × 10) dm + 9 dm = 60 dm + 9 dm = 69 dm
c. 9 cm 7 mm into mm
9 cm 7 mm = 9 cm + 7 mm = (9 × 10) mm + 7 mm

= 90 mm + 7 mm = 97 mm

Exercise 9A

1. Convert the following into m.
a. 8 km b. 12 km c. 24 km d. 96 km
e. 8 km 417 m f. 26 km 42 m g. 56 km 18 m h. 13 km 5 m
2. Convert the following into dm.

a. 13 m b. 15 m c. 39 m d. 412 m
e. 12 m 8 dm f. 19 m 9 dm g. 109 m 2 dm h. 3 m 5 dm

3. Convert the following into cm.
a. 9 m b. 15 m c. 63 m d. 150 m

e. 16 m 40 cm f. 17 m 82 cm g. 30 m 5 cm h. 5 m 62 cm
4. Convert the following into mm.
a. 10 cm b. 50 cm c. 29 cm d. 180 cm

e. 16 cm 3 mm f. 25 cm 8 mm g. 35 cm 8 mm h. 3 cm 11 mm

Conversion of Smaller units of Length into Bigger units

To convert a smaller unit into a bigger unit, we need to divide the smaller unit.
The following examples will help you understand the conversion of units of length.

example 1. Convert the following into metres.

a. 300 cm b. 500 cm
Solution. a. We know that 100 cm = 1 m.
300 cm = (300 ÷ 100) m = 3 m
b. 500 cm = (500 ÷ 100) m = 5 m

example 2. Convert the following into kilometres.

a. 3000 m b. 8000 m
Solution. a. 3000 m (3000 ÷ 1000) km = 3 km
b. 8000 m = (8000 ÷ 1000) km = 8 km

152 Mathematics 4