Significant Figures Calculator

Number

Round to, significant figures

Result

Significant figures now4
After rounding0.00452
Scientific notation4.52e-3
Decimal places6
About the zerosНули в конце после запятой значащие

Leading zeros never count, trailing ones depend

How many significant figures a number carries, rounding to a chosen count, and the result in scientific notation.

Significant figures record how precisely a number was measured. The rules are short but zeros cause trouble: leading zeros are never significant, zeros between digits always are, and trailing zeros depend on whether a decimal point is present.

0.004520 has four significant figures: the three leading zeros do not count, but the final zero does, because nobody writes it without reason. A whole number like 1200 is genuinely ambiguous.

What this calculator shows

How many significant figures the entered number has
The result rounded to the count you choose
Scientific notation, where the count is never ambiguous

What to keep in mind

The number is analysed as text, so 1.50 and 1.5 give different counts — which is exactly right.
Whole numbers with trailing zeros are ambiguous; scientific notation removes the ambiguity.

FAQs

Do trailing zeros count?

After a decimal point, yes: 1.50 has three. In a whole number like 1200 there is no single answer, which is why science writes 1.2 × 10³ or 1.200 × 10³ instead.

How many figures should a result keep?

As many as the least precise input. 2.5 times 3.42 gives 8.55, but it should be written 8.6 — two figures, matching the 2.5.

How is this different from decimal places?

Significant figures count from the first non-zero digit; decimal places count from the point. 0.004520 has four significant figures and six decimal places.

Why use scientific notation?

It states the number of significant figures unambiguously and handles very large and very small numbers cleanly.

Worked example

The number 0.004520

Input: 0.004520, round to 3 significant figures

Output: 4 significant figures, rounded to 0.00452

Note: The leading zeros only fix the magnitude. In scientific notation it is 4.520 × 10⁻³, which makes the count of four obvious.

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Significant Figures Calculator

Result

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