Rounding off Decimal Fractions

Till now we have learnt rounding off whole numbers to ten, hundred thousand and so on. Now this topic would discuss on rounding off decimal fraction to nearest ones.

In our daily life most of the time we round off decimal fraction to its nearest ones specially when buying shoes, clothes or grocery items. Hence rounding off decimal fraction finds a wide application in our day to day life.

Real life situations where rounding off decimal fractions is required:

I: Alex bought a pair of shoes costing $252.95. He paid $ 253. So we can say that $252.95 has been rounded off to $253

II: Mary bought different grocery items from the local shop which cost her $ 586.27. She paid to the shopkeeper $586. So, we can say that $586.27 has been rounded off to $586.

Rules for Rounding to Nearest Ones:

1. If the digit in the tenths place is 0, 1, 2, 3, or 4 then after the decimal the following digits will be replaced by zero.

2. If the digit in the tenths place is 5, 6, 7,  or 9 then the ones digit will be increased by 1 and all digits after the decimal are reduced to 0.

Here are few examples to illustrate rounding off decimal fractions

1. Round off the following decimal fraction:

(i) 87.52

(ii) 26.23

(iii) 95.01

(iv) 63.95

Solution:

(i) 88

The digit in the tenths place is 5 hence the ones digit would be increased by 1 that means the whole number 87 should be increased by 88

(ii) 26

The digit in the tenths place is 2 that is less than 5 hence the digits after the decimal place will be replaced by zero. So, we can say that 26.23 should be rounded to 26.

(iii) 95

Since the digit in tenths place is 0 which is less than 5 so all the digits after the decimal would be replaced by zero. So, 95.01 should be rounded to 95

(iv) 64

9 is the digit in tenths place which is more than 5 hence the digit in ones place of the whole number 63 should be increased by 1 and would become 64.

2. Round off the following decimal fraction:

(i) 96.873

(ii) 74.231

(iii) 745.96

(iv) 652.50

Solution:

(i) 97

As the digit in the tenths place is 8 which is more than 5 hence the ones digit in the whole number will be increased by 1 that is it will be rounded off to 97.

(ii) 74

The digit in tenths place is 2 that is less than 5 hence the digits after the decimal point should be replaced by zero. Therefore, 74.231 should be rounded to 74.

(iii) 746

The tenths digit is 9 which is more than 5 hence the ones digit in the whole number part should be increased by 1 to make it 746. Hence, 745.96 should be rounded to 746

(iv) 653

652.50 should be rounded to 653 as we know if the digit in the tenths place is equal to or greater than 5 then the ones digit in the whole number part should be increased by 1. Hence, 652.50 is rounded to 653.

5th Grade Math

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