Significant Figures Calculator

Non-zero digits always count; zeros between them count; leading zeros never do (0.00456 has three); trailing zeros count only with a decimal point (0.004560 has four, but 4500 is ambiguous — write 4.50 × 10³ to claim three).

Significant figures encode measurement precision — reporting 9.81 claims you measured to the hundredth. Calculations shouldn't grow precision: multiply values with 3 and 2 sig figs and the honest answer carries 2. Scientific notation removes every ambiguity.