Sig Fig Rules Calculator

40.0 has 3 significant figures. The 4 is non-zero, the 0 in the ones place is significant because a decimal point follows it, and the trailing 0 after the decimal also counts.

40.00 has 4 significant figures. The 4 counts, and all three trailing zeros after the decimal point are significant.

It is ambiguous. With no decimal point, 40 could have 1 or 2 significant figures depending on how the value was measured. To make it unambiguous, write 4.0 x 10^1 (2 sig figs) or 4 x 10^1 (1 sig fig).

100.0 has 4 significant figures. The 1 is non-zero, both 0s in the whole number are significant because there is a decimal point, and the trailing 0 after the decimal counts.

100.00 has 5 significant figures. With a decimal and trailing zeros, every digit becomes significant under the trailing-zero rule.

It is ambiguous. 100 could have 1, 2, or 3 sig figs without more context. Write 1.00 x 10^2 to fix it at 3 sig figs, or 1 x 10^2 for 1 sig fig.

0.500 has 3 significant figures. The leading zero before the decimal does not count, the 5 is non-zero, and both trailing zeros after the decimal count.

0.0030 has 2 significant figures. Leading zeros never count. The 3 is significant, and the trailing 0 after the decimal counts.

0.020 has 2 significant figures. Leading zeros (0.0) do not count, the 2 is significant, and the trailing 0 after the decimal counts.

0.00340 has 3 significant figures. Leading zeros do not count. The 3, 4, and trailing 0 after the decimal are all significant.

It is ambiguous. 1200 could have 2, 3, or 4 sig figs. Use scientific notation: 1.2 x 10^3 (2), 1.20 x 10^3 (3), or 1.200 x 10^3 (4).

4.0 has 2 significant figures. The 4 is non-zero, and the trailing 0 after the decimal is significant.

It is ambiguous. 200 has 1, 2, or 3 sig figs depending on context. Use scientific notation (2 x 10^2, 2.0 x 10^2, or 2.00 x 10^2) to remove the ambiguity.

It is ambiguous. 5000 could have 1, 2, 3, or 4 sig figs. Without a decimal point, the trailing zeros are not classifiable. Scientific notation resolves it: 5 x 10^3 (1), 5.0 x 10^3 (2), 5.00 x 10^3 (3), or 5.000 x 10^3 (4).

It depends on position. Trailing zeros after a decimal point are always significant (e.g. 2.50 has 3 sig figs). Trailing zeros in a whole number without a decimal point are ambiguous (e.g. 300 might have 1, 2, or 3 sig figs).

Captive zeros are zeros that appear between non-zero digits. They are always significant. For example, in 1.007 the two zeros are captive and all 4 digits are significant.

They prevent you from claiming more precision than your measurements actually provide. In science, reporting a result with too many digits implies a level of accuracy your instruments may not support, which can lead to incorrect conclusions.

Exact numbers (like counting 12 eggs or using the conversion 1 inch = 2.54 cm exactly) have unlimited significant figures and never limit the precision of a calculation.

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