Page 130 - Start Up Mathematics_4
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The length from 0 to 1 is 1 cm, from 1 to 2 is 1 cm, and so on. This
shows that there are 10 millimetres (mm) in 1 cm. Hence millimetre
0 1 is a smaller unit of measuring length. 10 mm = 1 cm
Look at the following table to know the various units for measuring length.
(km) kilometre
× 10 1/10
(hm) hectometre
× 10 (dam) decametre 1/10
× 10 (m) metre 1/10
× 10 (dm) decimetre 1/10
× 10 (cm) centimetre 1/10
× 10 1/10
(mm) millimetre
To convert from a bigger unit to a smaller unit, multiply the value by 10 as many times till
you reach that unit. For example, 1 km = (10 × 10) dam = 100 dam and 1 m = (10 × 10 ×
10) mm = 1,000 mm.
1
Similarly, to change from a smaller unit to a bigger unit, multiply the value by as many
1 1 1 1 10
times till you reach that unit. For example, 1 cm = × × dam = dam.
10 10 10 1,000
Example 1: Fill in the blanks.
(a) 7 m = ____ cm (b) 6 cm = ____ mm
(c) 9 m 50 cm = ____ cm (d) 2 cm 15 mm = ____ mm
(e) 70 mm = ____ cm
Solution: Conversion Table
(a) 1 m = 100 cm
So, 7 m = 7 × 100 cm = 700 cm. 1 km = 10 hm 1 mm = 1 cm
(b) 1 cm = 10 mm 10
So, 6 cm = 6 × 10 mm = 60 mm. 1 hm = 10 dam 1 cm = 1 dm
(c) 9 m 50 cm = 900 cm + 50 cm 10
= 950 cm 1 dam = 10 m 1 dm = 1 m
So, 9 m 50 cm = 950 cm. 10
(d) 2 cm 15 mm = 20 mm + 15 mm 1 m = 10 dm 1 m = 1 dam
= 35 mm 10
So, 2 cm 15 mm = 35 mm. 1 dm = 10 cm 1 dam = 1 hm
1 10
(e) 1 mm = cm
10 1 cm = 10 mm 1 hm = 1 km
1 10
So, 70 mm = 70 × cm = 7 cm.
10
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