## Ncert Solutions for Class 6 Maths Chapter 8 Decimals Exercise 8.5:-

**Exercise 8.5**Ā Class 6 maths NCERT solutions Chapter 8 Decimals pdf download:-

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### Ncert Solution for Class 6 Maths Chapter 8 Decimals Exercise 8.5 Tips:-

MULTIPLICATION OF DECIMAL NUMBERS

Reshma purchased 1.5kg vegetable at the rate of ` 8.50 per kg. How much money should

she pay? Certainly it would be ` (8.50 Ć 1.50). Both 8.5 and 1.5 are decimal numbers.

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So, we have come across a situation where we need to know how to multiply two deci-

mals. Let us now learn the multiplication of two decimal numbers.

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First we find 0.1 Ć 0.1.

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Thus, 0.2 Ć 0.3 = 0.06.

Observe that 2 Ć 3 = 6 and the number of digits to the right of the decimal point in

0.06 is 2 (= 1 + 1).

Check whether this applies to 0.1 Ć 0.1 also.

Find 0.2 Ć 0.4 by applying these observations.

While finding 0.1 Ć 0.1 and 0.2 Ć 0.3, you might have noticed that first we

multiplied them as whole numbers ignoring the decimal point. In 0.1 Ć 0.1, we found

01 Ć 01 or 1 Ć 1. Similarly in 0.2 Ć 0.3 we found 02 Ć 03 or 2 Ć 3.

Then, we counted the number of digits starting from the rightmost digit and moved

towards left. We then put the decimal point there. The number of digits to be counted

is obtained by adding the number of digits to the right of the decimal point in the

decimal numbers that are being multiplied.

Let us now find 1.2 Ć 2.5.

Multiply 12 and 25. We get 300. Both, in 1.2 and 2.5, there is 1 digit to the right

of the decimal point. So, count 1 + 1 = 2 digits from the rightmost digit (i.e., 0) in 300

and move towards left. We get 3.00 or 3.

Find in a similar way 1.5 Ć 1.6, 2.4 Ć 4.2.

While multiplying 2.5 and 1.25, you will first multiply 25 and 125. For placing the

decimal in the product obtained, you will count 1 + 2 = 3 (Why?) digits starting from

the rightmost digit. Thus, 2.5 Ć 1.25 = 3.225

Find 2.7 Ć 1.35.

In the table, you wrote the decimal number, given its place-value expansion. You can

do the reverse, too. That is, given the number you can write its expanded form. For

example, 253.417 = 2 Ć 100 + 5 Ć 10 + 3 Ć 1 + 4 Ć

John has ` 15.50 and Salma has ` 15.75. Who has more money? To find this we need

to compare the decimal numbers 15.50 and 15.75. To do this, we first compare the digits

on the left of the decimal point, starting from the leftmost digit. Here both the digits 1 and

5, to the left of the decimal point, are same. So we compare the digits on the right of the

decimal point starting from the tenths place. We find that 5 < 7, so we say

15.50 < 15.75. Thus, Salma has more money than John.

If the digits at the tenths place are also same then compare the digits at the hundredths

place and so on.

Now compare quickly, 35.63 and 35.67; 20.1 and 20.01; 19.36 and 29.36.

While converting lower units of money, length and weight, to their higher units, we are

required to use decimals. For example, 3 paise = `

3

100 = ` 0.03, 5g =

5

1000 kg

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= 0.005 kg, 7 cm = 0.07 m.

Write 75 paise = ` ______, 250 g = _____ kg, 85 cm = _____m.

We also know how to add and subtract decimals. Thus, 21.36 + 37.35 is