0.1 + 0.2
= 0.3
The exact sum is three tenths.
Exact Decimal Calculator
Add, subtract, multiply, and divide decimals using exact fractions. Avoid floating-point errors such as 0.1 + 0.2.
How this calculation works
A decimal is parsed as an integer numerator over a power of ten. Arithmetic operates on those fractions and reduces the result. A reduced fraction has a terminating decimal when its denominator has no prime factors other than two and five; otherwise its decimal expansion repeats.
Inputs and accuracy
Decimals are accepted for addition, subtraction, multiplication, division, power, and square. Integer-only operations reject fractional inputs. A precision selector controls rounded displays, not the underlying exact fraction.
When to use it
Check decimal arithmetic for measurements or financial calculations without introducing binary floating-point artifacts. This tool does not automatically apply currency-specific rounding or accounting rules.
Worked examples
1 ÷ 0.3
= 10/3
The fraction 10/3 is exact even though its decimal repeats.
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