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.
- 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.
Next step: Miscellaneous
