Grade 11 · Chemistry
Significant figures
Why it matters
Counting significant figures and rounding correctly in calculations.
Core20m readingPrerequisite: Derived quantities and density
What are significant figures?
Short answer
Significant figures are the digits in a measurement that carry meaningful precision — all certain digits plus one estimated digit. They communicate how precise a measurement is. In calculations, the result is rounded so it is no more precise than the least precise value used: addition keeps the fewest decimal places, multiplication keeps the fewest significant figures.
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Frequently asked questions
- Are trailing zeros significant?
- Trailing zeros are significant only if there is a decimal point; 100 has one significant figure but 100. has three.
- How many significant figures does a calculation keep?
- For multiplication and division, the fewest significant figures of any value; for addition and subtraction, the fewest decimal places.