Class 11 Physics Units and Measurements Rules for Rounding off the uncertain digits

Rules for Rounding off the uncertain digits

Rounding off is necessary to reduce the number of insignificant figures to adhere to the rules of arithmetic operation with significant figures.

Rule Number

Insignificant Digit

Preceding Digit

Example (rounding off to two decimal places)

1

Insignificant digit to be dropped is more than 5

Preceding digit is raised by 1.

Number – 3.137

Result – 3.14

2

Insignificant digit to be dropped is less than 5

Preceding digit is left unchanged.

Number – 3.132

Result – 3.13

3

Insignificant digit to be dropped is equal to 5

If preceding digit is even, it is left unchanged.

Number – 3.125

Result – 3.12

4

Insignificant digit to be dropped is equal to 5

If preceding digit is odd, it is raised by 1.

Number – 3.135

Result – 3.14

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