Calculations involving significant figures

Now that you've learned the importance of recording measurements to the proper number of significant figures, it is very likely that you will be doing calculations with these measurements. The type of calculations that you will most likely carry out are the following types of mathematical operations:

It is important to know how to determine the proper number of significant figures in your answer AFTER you have completed mathematical manipulations of the measurements.

Example

Calculate the area of the table-top based on the following measurements:

width = 50.996 cm
length = 75.4 cm

To calculate the area of the table-top, the area would equal 50.996 cm x 75.4 cm. The calculator answer is

When you record the area of the table-top, should you record area = 3845.0984 cm² (No!)

The calculator displays too many figures. You need to know some rules in determining the proper number of significant figures of an answer which resulted from a mathematical operation.

After applying the rules for multiplication and division, the answer is 3.85 x 10³ cm².

Content suitability

BCIT courses: CHEM 0011

Calculations involving significant figures