Which digits count, and why
Sig Fig Counter
Type a number to see each digit colour-coded as significant, a captive zero, a leading zero, or an ambiguous trailing zero — with a digit-by-digit explanation.
2
significant figures
1
2
0
0
0 Non-zero (significant)
0 Trailing zero, no decimal (ambiguous)
This number is ambiguous
Trailing zeros in a plain integer may or may not be significant, so 1200 could have 2 to 4 significant figures. Under the School Standard default it is read as 2. Write it in scientific notation to state the precision you mean:
- 2 sig figs 1.2 × 10^3
- 3 sig figs 1.20 × 10^3
- 4 sig figs 1.200 × 10^3
Digit-by-digit breakdown
- 1 thousands place Non-zero digit — always significant.
- 2 hundreds place Non-zero digit — always significant.
- 0 tens place Trailing zero with no decimal point — ambiguous; not counted by default.
- 0 ones place Trailing zero with no decimal point — ambiguous; not counted by default.
Scientific
1.2 × 10^3
E-notation
1.2e3
How each kind of digit is counted
| Digit type | Significant? | Example |
|---|---|---|
| Non-zero digit | Always | 123 → 3 |
| Captive zero (between significant digits) | Always | 4008 → 4 |
| Leading zero | Never | 0.00456 → 3 |
| Trailing zero with a decimal point | Yes | 1.200 → 4 |
| Trailing zero, no decimal point | Ambiguous | 1200 → 2, 3, or 4 |
Need arithmetic or rounding with the same rule explanations? Use the full Significant Figures Calculator.