Math

Fraction Calculator

Add, subtract, multiply, and divide fractions with automatic simplification.

Add, subtract, multiply, or divide two fractions and get the answer simplified to lowest terms, plus the decimal equivalent. Type fractions like 1/2 and 3/4 — the calculator finds common denominators and reduces the result automatically.

Introduction

Fractions represent parts of a whole: the denominator says how many equal parts the whole is split into, and the numerator says how many of those parts you have. Adding and subtracting fractions requires a common denominator — you cannot add thirds and eighths directly, any more than you can add apples and oranges. The standard move is to convert each fraction to an equivalent one with the least common denominator, add or subtract the numerators, and keep the denominator. Multiplication is simpler: multiply straight across, numerators times numerators and denominators times denominators. Division is multiplication by the reciprocal: flip the second fraction and multiply, which is why dividing by 1/2 doubles a number.

The classic mistakes are adding denominators (1/2 + 1/3 is not 2/5, it is 5/6) and forgetting to simplify the result. Always reduce the final answer by dividing numerator and denominator by their greatest common divisor: 10/12 becomes 5/6, and 4/8 becomes 1/2. Mixed numbers add one more step — convert 1 and 3/8 to the improper fraction 11/8 before operating, then convert back at the end. This calculator shows each step so you can follow the common-denominator and reciprocal logic rather than just copying an answer, which is what actually builds the skill for exams. One more tool for the kit: converting between fractions, decimals, and percents fluently. 3/8 is 0.375 is 37.5 percent — divide the numerator by the denominator for the decimal, multiply by 100 for the percent. Kitchen measuring cups (1/4, 1/3, 1/2) reward this fluency daily: doubling a recipe that calls for 2/3 cup gives 4/3 = 1 and 1/3 cups, and knowing that 1/3 cup is about 5 tablespoons plus a teaspoon saves a conversion chart lookup.

How it's calculated

Addition and subtraction use a common denominator (a/b ± c/d = (ad ± bc)/bd); multiplication multiplies straight across; division flips the second fraction and multiplies. Every answer is reduced with the greatest common divisor.

Worked examples

3/4 + 5/8

The least common denominator of 4 and 8 is 8. Convert: 3/4 = 6/8 (multiply top and bottom by 2). Add the numerators: 6/8 + 5/8 = 11/8. As a mixed number that is 1 and 3/8, since 8/8 = 1 with 3/8 left over. Decimal check: 0.75 + 0.625 = 1.375, and 11/8 = 1.375 — matches.

(2/3) / (4/5)

Flip the second fraction and multiply: 2/3 x 5/4 = 10/12. Simplify by dividing top and bottom by their greatest common divisor, 2: 10/12 = 5/6. Decimal check: 0.6667 / 0.8 = 0.8333, and 5/6 = 0.8333 — matches. Intuition check: dividing by 4/5 (which is less than 1) should give an answer bigger than 2/3, and 5/6 > 4/6 = 2/3. Consistent.

Frequently asked questions

How do I add 1/2 + 1/4?

Enter 1/2 and 1/4 with the Add operation — the answer is 3/4 (0.75). The calculator converts both to quarters, then adds.

Does it simplify the answer?

Yes. Every result is reduced to lowest terms automatically — for example 2/3 × 3/4 = 6/12 is shown as 1/2.

Can I divide fractions?

Yes. Division flips the second fraction and multiplies: 1/2 ÷ 1/4 = 1/2 × 4/1 = 2.

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References