Page 197 - New Medley 5 Semester 1

Need of Decimals

In our day-to-day life, we have to deal many situations like expressing the

amount of money, weights, heights, quantities of liquid, etc., where we use
decimals. Let us discuss a situation here to recall what we learnt in Class
4. Can you guess how thick a postcard or your pencil tip is? It is about 1
mm. Where do you see 1 mm measure? Observe your ruler markings from 1
to 15. The distance between two consecutive numbers is 1 cm. Further, each

one is divided into 10 equal parts. This one division shows 1 mm. That means,
1
1 mm is tenth part of 1 cm. Hence, 1 mm = cm. It also can be written
10
as .1 cm or 0.1 cm. The point (.) here used is known as the decimal. It is

used to separate the whole number and the decimal part.

Do you know the length of a 10-rupee note? It is 13 cm 5 mm. It is written
in centimetre as 13.5 cm.

In the same way, if your height is 1 m 35 cm, you can write it as 1.35 m
35
because 35 cm = m or 0.35 m.
100
How to Read and Write a Decimal

Have you thought what places are to the right of the ones place in a place-

value chart?
In a place-value chart, the value of the places decreases 10 times when
we move from one place to the next place in its right. Therefore, the place

1
value of the first place next to ones becomes (one-tenth), the second
10

1 1
place (one-hundredth), the third place (one-thousandth) and
100 1000

so on. We put a decimal to separate these places.

Hundreds Tens Ones Tenths Hundredths Thousandths
. Decimal 1 1 1
(H) (T) (O) (TTh) (HTh) (ThTh)
100 10 1 10 100 1000

.1 .01 .001

Whole number part Decimal part
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