Math Guides

Significant Figures Rules

By SC Editorial 2026-05-30 6 min read

Significant figures (sig figs) indicate the precision of a measurement. Reporting too many digits implies false precision; too few wastes information.

Counting Rules

  1. Non-zero digits are always significant
  2. Zeros between non-zero digits count (1002 has 4 sig figs)
  3. Leading zeros never count (0.0045 has 2 sig figs)
  4. Trailing zeros after a decimal count (3.50 has 3 sig figs)

Practice with the Significant Figures Calculator.

Operations

Addition/subtraction: round to least decimal places. Multiplication/division: round to fewest sig figs.

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