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\\September 30, 2025 9:51 AM Bharat Arora P-9 Reader _________________________ Date: ___________________74

MeaSuring Length

We know that the base unit to measure length is the metre (m). Units of length

bigger than the 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 smaller than the metre are km hm dam m dm cm mm
÷10
decimetre (dm), centimetre (cm) and millimetre ÷100 ÷10 ÷100
(mm). ÷1000 ÷1000
Bigger units
1 m = 10 dm = 100 cm = 1000 mm

1 dm = 10 cm = 100 mm

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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