Fraction Calculator

Fraction homework comes down to four operations and one habit: simplifying at the end. This calculator does both for fractions and mixed numbers, shows the answer as a fraction, a mixed number and a decimal, and turns decimals back into fractions.

How to Use It

1. Choose Two Fractions or Decimal to Fraction.
2. For two fractions, pick an Operation, then enter each number: an optional whole part, the numerator on top and the denominator below.
3. For a decimal, type it in, such as 0.375.
4. Press Calculate to see the answer in lowest terms, as a mixed number when it’s bigger than 1, and as a decimal.

How It Works

Each operation follows the usual rules for $\frac{a}{b}$ and $\frac{c}{d}$:

Subtraction works like addition with a minus sign. A mixed number is turned into an improper fraction first: $2\tfrac{1}{3} = \frac{7}{3}$. The answer is then divided through by the greatest common divisor of its numerator and denominator, so it’s in lowest terms.

A decimal becomes its digits over a power of ten, simplified: $0.375 = \frac{375}{1000} = \frac{3}{8}$. Past 6 decimal places, the calculator finds the simplest fraction that’s extremely close and says so.

Worked Example

Add $1\tfrac{1}{2}$ and $2\tfrac{1}{3}$:

Tips and Common Mistakes

• Don’t add denominators. $\frac{1}{2} + \frac{1}{3}$ is $\frac{5}{6}$, not $\frac{2}{5}$.
• Flip only the second fraction when dividing. Then multiply as usual.
• Mind the sign of a mixed number. $-1\tfrac{1}{6}$ means $-\frac{7}{6}$, so put the minus sign on the whole part.
• Simplify at the end. Cross-multiplying makes big numbers; the calculator reduces them for you.
• A denominator can never be 0. Neither can the fraction you divide by.