Practical guide · 6 min read
Significant Figures and Rounding Rules
Report calculated results with precision that matches the measurements.
Significant figures communicate measurement precision rather than the calculator's display capacity.
Multiplication and division
Match the result to the factor with the fewest significant figures.
Addition and subtraction
Match the result to the least precise decimal place.
Round once
Carry extra digits through the work and round only the final value to avoid accumulated error.
Put it into practice
Try the related calculator
Use the method above with an interactive tool that keeps the equation and units visible.
Open calculatorEditorial note
This guide is educational. Examples are deliberately compact and cannot cover every model, course convention, or laboratory condition. See our methodology for how formulas and examples are reviewed.