Rounding of decimals would be really useful for estimating amounts of money, duration of time, measure of distances and many other physical quantities.

**Rounding of Decimals**

Rounding of decimals would be really
useful for estimating amounts of money, duration of time, measure of distances and
many other physical quantities. Let us learn the same here.

**MATHEMATICS ALIVE - Decimals
in real life**

You can round decimals just in the same
way as you round whole numbers.

**To round a decimal** **:**

1. First
underline the digit that is to be rounded. Then look at the digit to the right of
the underlined digit.

2. If that
digit is less than 5, then the underlined digit remains the same.

3. If that
digit is greater than or equal to 5, add 1 to the underlined digit.

4. After rounding of, ignore all the
digits after the underlined digit.

** **

__Example 1.1____ __

Round 2.367 to the nearest whole number.

**Solution**

Underline the digit to be rounded - __2__.*3*67

Since the digit next to the underlined
digit is 3 which is less than 5, the underlined digit 2 remains the same.

Also look at the number line shown below :

On the number line, we observe that
2.3 is closer to 2.0 than 3.0

Hence, the rounded value of 2.367 to
the nearest whole number is 2.

** **

__Example 1.2____ __

Round 99.95 to the nearest tenth place.

**Solution**

Underline the digit to be rounded 99.__9__*5*.

Since the digit right to the tenth place
is 5, we add 1 to the tenth place (underlined digit) of 99.95 and we get 100.0.

Look at the number line shown below:

So, the rounded value of 99.95 is
100.0.

** **

__Example 1.3__

Round 52.6583 upto 2 places of decimal.

**Solution**

Round 52.6583 upto 2 places of decimal
means round to the nearest hundredths place.

Underline the digit in the hundredth
place of 52.6583 gives 52.6** 5**83.

We observe that the digit after the hundredth
place value is 8 which is more than 5.

Therefore, we should add 1 to the underlined
digit. Hence, we get 52.66.

So the rounded value of 52.6583 upto
2 places of decimal is 52.66.

** **

__Example 1.4____ __

Round 189.0007 upto 3 places of decimal.

**Solution**

Round 189.0007 upto 3 places of decimal
means rounding to the nearest thousandth place

Underline the digit in the thousandth
place of 189.0007 gives 189.00__0__7

In 189.00__0__7 we observe that the
digit next to the thousandth place value is 7, which is greater than 5.

Therefore, we should add 1 to the underlined
digit. Hence, we get 189.001.

So the rounded value of 189.0007 upto
3 places of decimal is 189.001

Now a days calculators,
computers and even mobile phones were used for multiplication and division of decimals.
But, actually multiplication of decimals using logarithm tables will be more useful
and handy.

Tags : Number System | Term 3 Chapter 1 | 7th Maths , 7th Maths : Term 3 Unit 1 : Number System

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7th Maths : Term 3 Unit 1 : Number System : Rounding of Decimals | Number System | Term 3 Chapter 1 | 7th Maths

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