Decimal Calculator

Use + - * / ^ ( ) and % for remainder. Multiplication and division are done before addition and subtraction. In "words" mode, type the sum in plain English instead.
Name a value the expression may use, e.g. "l = 12, w = 7" with an expression of 2 * (l + w).
Changes how the answer is written out. It never changes the arithmetic.
Result
0.3
Basic Arithmetic Calculator
Unrounded result
0.3
Expression evaluated
0.1 + 0.2
Result with separators
0.3
Result as a fraction
3/10
Operation
Expression
Arithmetic used
Exact fractions
Worked out from ISO 80000-2, Quantities and units — Part 2: Mathematics (operator symbols and precedence) and 3 other sources.

How this is worked out

3 steps
  1. Evaluate 0.1 + 0.2 in exact fraction arithmetic.
  2. 1/10 + 1/5 = 3/10
  3. In binary floating point the same expression gives 0.30000000000000004; the exact value is 3/10 = 0.3.
Step-by-step workingtable
1/10 + 1/5 = 3/10

Results are general information, not financial, tax, legal, medical or engineering advice.