Rounded value
0.00456
Numeric value rounded to the requested number of significant figures.
Mathematics · Numbers & everyday maths
Significant figures calculator — count and round
Enter the number as written so trailing decimal zeros are preserved, then choose how many significant figures to keep.
Created v1.0
By Thibaut Grzelak, Mechanical Analysis Engineer
03
Results
Significant figures written
4
Count inferred from the entered notation.
Rounded scientific notation
4.56 × 10^-3
Results show up to four significant digits for readability; internal calculations retain full precision.
See calculation details
01Rounded value
Formula
xᵣ = [x]_nSubstitution
[0.00456]_3Result
0.00456
02Significant figures written
Formula
N = #(x)Substitution
#(0.00456)Result
4
01Formulas and symbols
Formulas used
xᵣ
x xᵣ to n significant figures
Round a finite value to n significant figures while preserving the input notation for the count.
| Symbol | Meaning |
|---|---|
| x | Number as written |
| n | Significant figures to keep n |
| xᵣ | Rounded value |
| N | Significant figures written |
| xₛ | Rounded scientific notation |
02Validation example
Reference numerical case
- 0.004560 contains 4 significant figures; rounded to 3 significant figures it is 0.00456 = 4.56 × 10^-3. Likewise, 0.000056 contains N = 2 written significant figures; requested at n = 3, it displays as 0.0000560 = 5.60 × 10^-5 without changing its numerical value.
03Count written precision, then round
Leading zeros are placeholders and are not significant. Zeros between non-zero digits are significant. Decimal trailing zeros are significant; plain integer trailing zeros use the stated convention.
04Limits and conventions
Significant-figure conventions vary for ambiguous trailing zeros. Use scientific notation when you need to state precision unambiguously.
05Common mistakes
Do not count leading zeros before the first non-zero digit. Do not confuse decimal places with significant figures.
06Practical questions
Why does 1200 have an ambiguous number of significant figures?
Without a decimal point or scientific notation, trailing integer zeros are commonly ambiguous. This calculator follows the convention that they are not significant.
Why enter the number as text?
The written zeros carry precision information. A numeric parser alone would make 1.230 indistinguishable from 1.23.
07Technical references
- Accuracy, precision and significant figures — OpenStax