Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
spacerUNIT # 1  
spacerspacerIntroduction
spacerspacerObjectives
spacerspacerReading

spacer1.1
Metric
spacerSystem
spacerSI System
spacerBritish System

spacer1.2 Temperature
spacerMeasure-
spacerments

spacer1.3 Scientific
spacerNotation

spacer1.4 Dimensional
spacerAnalysis

spacer1.5 Precision,
spacerAccuracy,
spacerUncertainty

spacerLimitation of the Measuring Instrument
spacerAnalysis of the Limitation of a Ruler
spacerAnalysis of the Limitation of another Ruler
spacer1.6 Significant
spacerFigures

spacerThe Magnitude and Reliability of the Measurement
spacerFive Rules for Determining the number of Significant Figures in a Measurement

spacer1.7 Calculations
spacerInvolving
spacerSignificant
spacerFigures
spacerRules for Rounding off Numbers
spacerRules for Addition  and Subtraction

spacerRules for Multiplication and Division

spacer1.8 Density
spacerDensity and Temperature
spacer1.9 Specific
spacerGravity
spacerspacerProblems
spacer1 | 2 | 3
   

MEASUREMENT

1.7 - Calculations Involving Significant Figures

1.7.3 - Rules for Multiplication and Division

The answer must contain the same number of significant figures as were present in the measurement with the fewest number of significant figures.

Question: A student measures the length of a table to be 120.2 cm and the width to be 29.5 cm. What is the area of the table. Express the answer with the proper number of significant figures.

Answer:

Step 1: To obtain the area of the table, we perform the following multiplication using the calculator.

29.5 cm x 120.2 cm = ?

The calculator displays the answer to be 3545.9. The unit is in cm2.

Step 2: Inspect each number and determine the number of significant figures in each number.

29.5
3 significant figures
(This measurement has the fewest number of significant figures.)
120.2
4 significant figures

The measurement 29.5 limits the number of significant figures in the answer to 3 significant figures.

The answer is 3.55 x 103 cm2; 3 significant figures.

Going back to the example in section 1.7, the answer is

3.85 x 103 cm2.

The answer has 3 significant figures because the length measurement is the measurement with the fewest significant figures (i.e. 3 significant figures). It limits the final answer to 3 significant figures.


Section 2.6
Mathematical Operations Involving Significant Digits ..p23

 

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