The four operations
Addition and subtraction need matching denominators, so the calculator rewrites both fractions over the product of the denominators, adds or subtracts the numerators and then simplifies. Multiplication is simpler: multiply across. Division turns into multiplication by the reciprocal.
Mixed numbers are converted to improper fractions first (2 1/2 becomes 5/2), and the answer is shown both as a fraction and as a mixed number so you can use whichever form your task needs.
Worked examples
1/2 + 1/3 = 3/6 + 2/6 = 5/6, or 0.8333 as a decimal. 1/2 − 3/4 = 2/4 − 3/4 = −1/4. 2 1/2 × 1 1/3 = 5/2 × 4/3 = 20/6 = 10/3, which is 3 1/3. And 3/4 ÷ 3/8 = 24/12 = 2.
Try these in the calculator to check your own working, which is a good way to learn how each step goes.
Where fractions show up
Fractions appear in cooking (halving a recipe that calls for 3/4 cup), carpentry (inches in fractions) and anywhere you split things into parts. The decimal and percentage lines in the result make it easy to switch between the forms.
For percentages of an amount use the percentage calculator, and for a longer expression with brackets try the scientific calculator.
Questions people ask
How do you add fractions with different denominators?
Find a common denominator, convert both fractions, add the numerators and simplify. For 1/2 + 1/3, the common denominator is 6: 3/6 + 2/6 = 5/6. The calculator multiplies the denominators and then reduces the result, which gives the same answer.
How do you multiply and divide fractions?
To multiply, multiply the numerators and the denominators: 2/3 × 3/4 = 6/12 = 1/2. To divide, flip the second fraction and multiply: 3/4 ÷ 3/8 = 3/4 × 8/3 = 24/12 = 2.
How do I enter a mixed number?
Fill in the whole part as well as the numerator and denominator. For 2 1/2 enter whole 2, numerator 1 and denominator 2. For a negative mixed number such as −1 1/2, put the minus sign on the whole part. The calculator treats the whole mixed number as negative, giving −3/2.
How do you simplify a fraction?
Divide the numerator and the denominator by their greatest common divisor. For 18/24 the greatest common divisor is 6, so the fraction is 3/4. The calculator does this automatically, so the result is always in lowest terms.
Why can’t the denominator be zero?
A fraction means the numerator divided by the denominator, and division by zero has no value. In the same way you cannot divide by a fraction that equals zero, such as 0/5. The calculator flags both.