Significant Figures Calculator

Count n digits starting from the first nonzero digit, then look at the next digit: 5 or above rounds up, below 5 leaves the kept digits as they are. For example, 1,234.567 to 3 sig figs is 1,230, and 0.000456 to 2 sig figs is 0.00046. The calculator above applies exactly this rule and shows the scientific-notation form so precision stays visible.

By the standard convention, 2 — the trailing zeros in a whole number without a decimal point are treated as placeholders. Write 1,500. (with a decimal point), 1.500 × 10³, or underline the last significant digit if you mean all four digits to be significant. Context matters: a population rounded to the nearest hundred is genuinely 3 sig figs, which plain text cannot show.

No. Leading zeros only locate the decimal point: 0.00456 has 3 significant figures (4, 5, 6), and 0.000 has none. This is the most common counting mistake in homework — remember that zeros between nonzero digits (1,024) are significant, but zeros before the first nonzero digit never are.

Decimal places count digits after the point; significant figures count meaningful digits from the first nonzero digit. 0.00046 has 5 decimal places but only 2 significant figures. Multiplication and division round by sig figs; addition and subtraction round by decimal places — the two rules track different kinds of error.

In binary floating point, 1.005 is stored as approximately 1.00499999…, so calculators that round the binary value produce 1.00. This tool rounds the decimal digit string directly, where the next digit is genuinely 5, giving 1.01. The same string-based approach protects other classic cases like 2.675 or 8.835.

The carry cascades all the way: 9.99 becomes 10 (1 × 10¹). The kept digit is 9, the next digit is 9, so it rounds up, and the carry turns the whole kept string to zero with a leading 1. The scientific-notation output is the reliable way to read such results — the plain form 10 hides that only 1 significant figure is claimed.

No — carry extra guard digits (one or two) through every intermediate step and round only the final answer. Rounding early compounds error: in a three-step chain, rounding each step to 3 sig figs can shift the final result in the last significant digit. The sig-fig rules for each operation apply to the inputs of that operation, not to trimmed intermediates.