Measurement and Significant Figures
All measurements have some degree of error. Significant figures show the precision of a measurement and help communicate accuracy in scientific and mathematical contexts.
What You Need to Know
Key Concept Diagram
Significant figures indicate the precision of a measurement
Leading zeros are not significant; trailing zeros after a decimal point are significant
To round to n significant figures, count n digits from the first non-zero digit
Measurements should be reported to an appropriate number of significant figures
Key Vocabulary
Significant figures
The meaningful digits in a number that indicate measurement precision
Precision
How finely a measurement is divided; more sig figs = more precise
Rounding
Reducing the number of digits while keeping the value approximately equal
Measurement error
The difference between a measured value and the true value
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
How many significant figures does 0.0450 have?
Question 2
Round 3.7864 to 3 significant figures.
Question 3
Why do scientists use significant figures?
Key Concepts Summary
- ●Significant figures indicate the precision of a measurement
- ●Leading zeros are not significant; trailing zeros after a decimal point are significant
- ●To round to n significant figures, count n digits from the first non-zero digit
- ●Measurements should be reported to an appropriate number of significant figures