Page 118 - Start Up Mathematics_3

To convert metres into centimetres, we multiply by 100. Quick Tip

For example, To convert m into cm,

3 m = (3 × 100) cm = 300 cm put two zeros to the
right of the number.
4 m = (4 × 100) cm = 400 cm

9 m = (9 × 100) cm = 900 cm

Example 3: Raju bought a blanket measuring
7 m 20 cm. How much is this length Mental Maths
in centimetres? (a) 2 m 40 cm = _____ cm

Solution: 7 m = (7 × 100) cm = 700 cm (b) 6 m 15 cm = _____ cm

7 m 20 cm = 700 cm + 20 cm = 720 cm (c) 11 m 50 cm = _____ cm

So, the blanket is 720 cm long.

Conversion of centimetres into metres

You already know that there are 100 centimetres in 1 metre. So to change a length
given in centimetres into metres, we divide by 100. For example,

100 cm = (100 ÷ 100) m = 1 m

200 cm = (200 ÷ 100) m = 2 m
1100 cm = (1100 ÷ 100) m = 11 m

Example 4: A piece of cloth is 198 cm long. Express its length in metres and
centimetres.

Solution: 198 cm = 100 cm + 98 cm

= 1 m + 98 cm = 1 m 98 cm

So, the cloth is 1 m 98 cm long.

Quick Tip

3 5 0 11 39
When we convert cm into m and cm, the
last two digits always stand for cm. 3 m 50 cm 11 m 39 cm

EXERCISE 8.1

1. Measure the following things using a 15 cm ruler and write their length.

(a) Length of your eraser = ____ cm (b) Length of a fork = ____ cm

(c) Length of a glue stick = ____ cm (d) Length of a thermometer = ____ cm

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