Round any number to a specified number of significant figures and understand sig fig rules.
Significant Figures Calculator
Math
Inputs
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Enter any number (decimals, scientific notation, or regular).
Enter the number of significant figures to round to.
Click Calculate to see the rounded result and scientific notation.
Significant figures (sig figs) are the meaningful digits in a number. Rules: non-zero digits always count; leading zeros never count; trailing zeros after a decimal point count; zeros between sig figs count.
3 sig figs — the leading zeros don't count, but the trailing zero after 5 does.