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Percentage Calculator
Find a percentage of a number, what percent one number is of another, or the whole from a part.
Decimal Calculator
Add, subtract, multiply or divide decimals exactly, without floating-point rounding errors.
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How to use this calculator
Enter your values. The result updates as you type; press Calculate to confirm and jump to the result on mobile. Use Share to send the calculator with your result.
Why exact decimal math matters
Most computers store decimals in binary, so 0.1 + 0.2 comes out as 0.30000000000000004. This calculator does the arithmetic on whole numbers scaled by powers of 10, so 0.1 + 0.2 = 0.3 exactly. The floating-point result is shown for comparison.
- Adding/subtracting: line up the decimal points.
- Multiplying: multiply as whole numbers, then count the total decimal places.
- Dividing: shift both decimal points so the divisor is a whole number.
Frequently asked questions
What is 0.1 + 0.2?
Exactly 0.3.
About this tool
- Written by
- [Author: to be assigned]
- Reviewed by
- Formula tests passed · human review pending
- Last updated
- 31 Oct 2026
See our methodology and editorial policy. Think something’s off? Report an error with this tool.
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