Are trailing zeros significant?
Only with a decimal point or explicit notation. 4,500 is ambiguous; 4,500. and 4.50 × 10³ each clearly indicate the intended precision.
Count significant figures in any number and round to a specified number of sig figs. Includes rules explanation and examples.
Count digits from the first non-zero digit. Multiplication/division: result keeps the fewest significant figures of the inputs. Addition/subtraction: keep the fewest decimal places.
4.56 × 1.4 = 6.384, reported as 6.4 (two significant figures). But 4.56 + 1.4 = 5.96, reported as 6.0 — one decimal place.
Only with a decimal point or explicit notation. 4,500 is ambiguous; 4,500. and 4.50 × 10³ each clearly indicate the intended precision.
No. 0.00420 has three significant figures — the 4, 2 and the trailing zero. Leading zeros only place the decimal point.
Addition is limited by absolute precision (decimal places), while multiplication is limited by relative precision (significant figures). Mixing the rules is the most common lab-report error.