Significant Figures Counter
Enter a number below to find its significant figures count and identify which digits are significant. Accepts whole numbers, decimals, and scientific notation (e.g., $3500$, $35.0056$, $3.5 \times 10^3$, or $3.5\text{e}3$).
How many significant figures? —
Significant digits are:
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Significant Figures Rules
Significant figures are the digits of a number that are meaningful in terms of accuracy or precision. Here’s how to identify them:
Digits that are SIGNIFICANT:
- Non-zero digits are always significant (e.g., $81$ has $2$ sig figs).
- Zeros between non-zero digits are always significant (e.g., $5200.38$ has $6$ sig figs).
- Trailing zeros are significant only when there is a decimal point present (e.g., $380.0$ has $4$ sig figs, but $78800$ has $3$ sig figs).
Digits that are NOT Significant:
- Leading zeros are never significant (e.g., $0.007$ has $1$ sig fig).
- Trailing zeros without a decimal point are generally not significant (e.g., $78800$ has $3$ sig figs).
Examples
| Number | How Many Sig Figs? | Significant Digits |
|---|---|---|
| $81$ | $2$ | $8, 1$ |
| $26.2$ | $3$ | $2, 6, 2$ |
| $0.007$ | $1$ | $7$ |
| $5200.38$ | $6$ | $5, 2, 0, 0, 3, 8$ |
| $380.0$ | $4$ | $3, 8, 0, 0$ |
| $78800$ | $3$ | $7, 8, 8$ |
| $78800.$ (with explicit decimal) | $5$ | $7, 8, 8, 0, 0$ |
References:
Khan, Salman “Significant Figures,” The Khan Academy.
Weisstein, Eric W. “Significant Digits,” MathWorld–A Wolfram Web Resource.