Formula
Addition uses a common denominator. The other operations follow the matching fraction rule, then the result is reduced:
a/b + c/d = (ad + bc) / bd
Subtraction changes the sign of the second numerator. Multiplication multiplies straight across. Division flips the second fraction.
Assumptions
- Denominators are not zero.
- Division by a zero numerator is rejected.
Worked example
1/2 plus 1/3 is 5/6.
Input definitions
- Numerator
- The top of the fraction.
- Denominator
- The bottom of the fraction. It cannot be zero.
Limitations
Results are rounded for display. This is a classroom calculation, not a measurement from a lab or a financial filing.
Questions
Is the answer reduced?
Yes. A result such as 2/4 is shown as 1/2.
Where do I turn an improper fraction into a mixed number?
Use the mixed-number calculator.