How many significant figures in 0.001?
0.001 has 1 significant figure.
Significant figures
Non-zero digit. Every non-zero digit is significant.Zero between digits. A zero between two non-zero digits is significant.Leading zero. Leading zeros only fix the decimal point, so they are not significant.Trailing zero after the point. Trailing zeros in a number with a decimal point are significant.Trailing zero, no point. Trailing zeros in a number without a decimal point are not counted. Write 1.00 × 10² to make them count.Digit of a in a × 10ⁿ. In a × 10ⁿ every digit of a is significant, including its zeros. Counted and defined numbers, such as 3 coins or 100 cm in a metre, are exact and have unlimited significant figures.
Tap a digit to see why it counts.
1significant figure
Scientific notation1 × 10−3
Round to
0.001→0.001
Nothing is dropped.
Add, subtract, multiply, divide
Add or subtract. The answer keeps as many decimal places as the number that has the fewest. Multiply or divide. The answer keeps as many significant figures as the number that has the fewest. The rounding is done once, on the exact result.
- 4.2374 significant figures
- 2.513 significant figures
Exact result1.68804780876
Multiply or divide: keep the fewest significant figures.
Reported1.693 significant figures
Digit by digit
- 000
Leading zero: does not countLeading zeros only fix the decimal point, so they are not significant.
- 1
Non-zero digit: countsEvery non-zero digit is significant.
1 × 10⁻³
Nearby numbers
Rounding a value? See 2.745 to 3 significant figures.
0.001: quick answers
How many significant figures does 0.001 have?
0.001 has 1 significant figure. In 0.001, the zeros at the start only fix the decimal point.
Why do the zeros at the start of 0.001 not count?
Zeros before the first non-zero digit only fix where the decimal point sits. 0.001 in scientific notation is 1 × 10⁻³, and no zero is left in the mantissa.
Can a number have fewer than one significant figure?
No. 0.001 already has the fewest, 1 significant figure.