Significant Figures (Sig Figs) Counter & Rounder
Count the number of significant figures in any decimal or scientific number, display scientific notation, and round values accurately following international sig fig arithmetic rules.
Calculated Results
Frequently Asked Questions
What are the fundamental rules for counting significant figures?
1. All non-zero digits are significant (1-9). 2. Zeros between non-zero digits are always significant (e.g., 405 has 3 sig figs). 3. Leading zeros before the first non-zero digit are never significant (0.004 has 1 sig fig). 4. Trailing zeros to the right of the decimal point are significant (0.004050 has 4 sig figs). 5. Trailing zeros in a whole number without a decimal point are ambiguous (e.g. 1,200 typically has 2 sig figs unless written as 1200. or 1.200 × 10³).
Why are trailing zeros after a decimal point significant?
Trailing zeros indicate measurement precision. Measuring '5.00 grams' signifies the scale measures accurately down to the hundredth of a gram (±0.01g), whereas '5 grams' only indicates precision to the nearest whole gram (±1g).
How do you round calculations using sig fig rules?
For multiplication and division: round the final answer to the same number of significant figures as the input measurement with the fewest sig figs. For addition and subtraction: round to the same number of decimal places as the measurement with the fewest decimal places.
What is the difference between scientific and engineering notation?
Scientific notation uses powers of 10 with a single non-zero digit before the decimal point (e.g. 4.5 × 10⁴). Engineering notation restricts exponents to multiples of 3 (10³, 10⁶, 10⁻³, 10⁻⁶), corresponding directly to SI metric prefixes (kilo, mega, milli, micro).