About Significant Figures in Whole Numbers
This page opens on 1200, the classic ambiguous case: it can have two, three or four significant figures depending on which zeros were measured. It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
By the usual convention, trailing zeros in a whole number with no decimal point are not significant, so 1200 has 2. If you tell the calculator the zeros were measured it counts 4, and 1200. with a decimal point has 4.
The way out is scientific notation: 1.2 × 10³ has two figures, 1.20 × 10³ has three and 1.200 × 10³ has four. Use it whenever the number of figures matters.
How to use Significant Figures in Whole Numbers
- Choose Count, Round, Arithmetic or Scientific notation.
- Type the number exactly as it was measured, keeping any trailing zeros: 0.00450, 1200, 1.20e3.
- For rounding, set how many significant figures to keep. For arithmetic, type the second number and choose the operation.
- Read the answer, then open the digit-by-digit reasons or the steps.
- For a whole number that ends in zeros, use the switch to say whether those zeros were measured.
Features
- Digit-by-digit rule explanation: leading, non-zero, captive and trailing zeros.
- Round to any number of significant figures from 1 to 50, half up.
- Add and subtract by decimal places, multiply and divide by significant figures.
- Scientific notation that keeps exactly the significant figures.
- E-notation input such as 1.20e3 and 4.5 x 10^-3.
- A clear note on the ambiguity of trailing zeros in whole numbers, with a switch.
- Exact decimal arithmetic, no floating-point surprises.
Resolving the ambiguity
Show the precision you mean with a decimal point or scientific notation.
1200 -> 2 (convention)
1200. -> 4
1.20 × 10³ -> 3Worked examples
1200 gives 2 (convention)
Trailing zeros without a decimal point are not counted.
1200. gives 4
The decimal point shows that the zeros are measured.
1200 with zeros counted gives 4
Use the switch when you know the zeros are measured.
Privacy: how it works
- Everything is calculated by code running in your browser tab. The numbers you enter are not sent to Ulkaa or to any other server, and there is nothing to sign in to.
Tips
- Write whole numbers that end in zeros in scientific notation, 1.20 × 10³, so nobody has to guess how many figures you meant.
- Keep extra digits in intermediate steps and round only the final answer.
- For a mixed calculation, apply the multiply rule and the add rule to each step separately and round at the end.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial and no credit card. Ulkaa Tool does the work with your own device, so there is no server bill to pass on to you.
Do I need an account?
No. There is no sign-up and no login. Open the page and use it. An Ulkaa account is not needed for anything on this tool.
Does it run in my browser?
Yes. Numbers are processed by code running in your browser tab, on your own device.
Is my data uploaded?
No. Numbers are never sent to Ulkaa or to anyone else. You can check this yourself by watching the Network tab in your browser developer tools while you use the tool.
How many significant figures does 1200 have?
Two by the common convention, but it is ambiguous. It could be two, three or four depending on the measurement.
How do I remove the ambiguity?
Write it in scientific notation, such as 1.20 × 10³, or add a decimal point (1200.) when all the zeros are significant.
More Significant Figures Calculator pages
- Significant Figures CalculatorType a measurement to count its significant figures, round it, calculate with it or write it in scientific notation.
- Round to Significant FiguresType a number and how many significant figures to keep.
- Significant Figures AdditionEnter two numbers to add or subtract them and keep the right precision.
- Significant Figures MultiplicationEnter two numbers to multiply them and keep the right significant figures.
- Significant Figures DivisionEnter two numbers to divide them and keep the right significant figures.
- Scientific Notation and Sig FigsType a number and get its scientific notation with the right number of digits.