About Scientific Notation and Sig Figs
This calculator converts a number to scientific notation, keeping exactly its significant figures, and converts E-notation or a × 10^n form back to plain digits. It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
The page opens on 0.00450, which is 4.50 × 10^-3. Writing 4.50 and not 4.5 matters: the trailing zero was measured, so it stays. In contrast 123000 is 1.23 × 10^5, because the trailing zeros of a whole number are not counted unless you say so.
Going the other way, 6.02e23 expands to 602 followed by 21 zeros, and keeps 3 significant figures. Scientific notation is the clearest way to show how many figures a number has.
How to use Scientific Notation and Sig Figs
- 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.
Scientific notation
Write the number as a mantissa between 1 and 10 times a power of ten.
0.00450 = 4.50 × 10^-3
123000 = 1.23 × 10^5Worked examples
0.00450 gives 4.50 × 10^-3
Three significant figures.
123000 gives 1.23 × 10^5
The trailing zeros are not counted.
6.02e23 gives 602 followed by 21 zeros
Keeps 3 significant figures.
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 do I write a number in scientific notation?
Move the decimal point until there is one non-zero digit before it, and multiply by 10 to the number of places you moved, negative if you moved right.
How do I show trailing zeros as significant?
Keep them in the mantissa: 1.200 × 10³ has four significant figures, while 1.2 × 10³ has two.
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.
- Significant Figures in Whole NumbersWhole numbers that end in zeros are ambiguous. See how many figures 1200 has and how to say what you mean.