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\\December 11, 2023 5:25 PM Bharat Arora P-6 Reader _________________________ Date: ___________________74

MeaSuring Length

We know that the base unit to measure length is metre (m). Units of length higher
than metre are kilometre (km), hectometre (hm) and decametre (dam).

1 km = 10 hm = 100 dam = 1000 m Smaller units

1 hm = 10 dam = 100 m ×1000 ×1000
×100
1 dam = 10 m ×100 ×10 ×10
Units of length lower than metre are decimetre km hm dam m dm cm mm
÷10
(dm), centimetre (cm) and millimetre (mm). ÷100 ÷10 ÷100
1 m = 10 dm = 100 cm = 1000 mm ÷1000 ÷1000

1 dm = 10 cm = 100 mm Bigger units
1 cm = 10 mm

conversion of Bigger units of Length into Smaller units

To convert a bigger unit into a smaller unit, we need to multiply the bigger unit. The

following examples will help you understand the conversion of units of length.
example 1: Convert the following as directed:

(a) 7 m into cm (b) 14 m 18 cm into cm (c) 4 km 250 m into m
Solution: (a) We have, 1 m = 100 cm
So, 7 m = 7 × 100 cm = 700 cm

(b) 14 m 18 cm = 14 m + 18 cm
= (14 × 100) cm + 18 cm ( 1 m = 100 cm)

= 1400 cm + 18 cm = 1418 cm
(c) We have,

1 km = 1000 m
So, 4 km = 4 × 1000 m = 4000 m
4 km 250 m = 4000 m + 250 m = 4250 m

example 2: Convert the following:
(a) 8 m into dm (b) 8 cm 7 mm into mm (c) 7 m 9 dm into dm

Solution: (a) We have,
1 m = 10 dm
So, 8 m = (8 × 10) dm = 80 dm

(b) We have,
1 cm = 10 mm

So, 8 cm = (8 × 10) mm = 80 mm

8 cm 7 mm = 80 mm + 7 mm = 87 mm

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