## Use in calculations

This page is meant to teach you how to use the correct number of significant figures when doing arithmetic.

- When
__addition or subtraction__happens between two numbers:- Rule: See which of the two numbers has the least number of
**digits to the right of the decimal point**. The answer should have the same number of digits to the right of the decimal point. - Example 1: Add 89.321 to 1.1The calculator will show 90.421 but you will round off and write the value as 90.4.
- Example 2: Subtract 36.5325 from 191.13The calculator will show 154.5975 but you will round off and write the value as 154.60.

- Rule: See which of the two numbers has the least number of
- When
__multiplication or division__happens between two numbers:- Rule: See which of the two numbers has the least number of
**significant figures**. The answer should have the same number of significant figures. - Example 1: Multiply 28.2 with 1.2366The calculator will show 34.87212 but you will round off and write the value as 34.9.
- Example 2: Divide 99 by 3.14The calculator will show 31.52866242038217 but you will round off and write the value as 32.

- Rule: See which of the two numbers has the least number of

Next step: Miscellaneous