How to use it
- Type the first number in First number: a fraction such as 3/4, a mixed number such as 1 1/2, or a decimal such as 0.75.
- Choose the Operation: add, subtract, multiply or divide.
- Type the second number in Second number. The answer appears as you type.
- Read Answer in lowest terms, then the mixed number and the decimal, and check each line under How it is worked out.
How the four operations work
To add or subtract fractions, both must have the same denominator. The calculator uses the least common multiple (LCM) of the two denominators, the smallest number that both divide into. So 3/4 + 1/6 is worked over 12, not over 24.
To multiply, multiply the numerators and multiply the denominators. To divide, multiply by the reciprocal of the second fraction: turn it upside down and multiply.
a/b + c/d = (a × (L ÷ b) + c × (L ÷ d)) ÷ L
L = LCM(b, d)Simplifying with the GCD
The answer is reduced to lowest terms by dividing the top and the bottom by their greatest common divisor (GCD). The GCD is found with Euclid's algorithm. For example, the GCD of 42 and 56 is 14, so 42/56 is 3/4.
A fraction whose top and bottom have no common divisor other than 1 is already in lowest terms. A decimal such as 0.75 is first written as 75/100 and then simplified in the same way.
What the calculator accepts
- Whole numbers, such as 5 or -5.
- Fractions, such as 3/4 or -2/3. Spaces around the slash are allowed.
- Mixed numbers, such as 1 1/2, which means 1 + 1/2 = 3/2.
- Decimals, such as 0.75. In Turkish, write 0,75.
- Not supported: more than two numbers in one calculation, powers, and fractions inside fractions.
Worked example: 3/4 + 1 1/2
The second number is a mixed number: 1 1/2 is 3/2. The denominators are 4 and 2, and their least common denominator is 4, so 3/2 is written as 6/4.
The numerators add to 3 + 6 = 9, so the sum is 9/4. The GCD of 9 and 4 is 1, so 9/4 is already in lowest terms. As a mixed number it is 2 1/4, and as a decimal it is 2.25.
| Result | |
|---|---|
| Answer in lowest terms | 9/4 |
| As a mixed number | 2 1/4 |
| As a decimal | 2.25 |
Frequently asked questions
How do I enter a mixed number?
Type the whole part, a space, then the fraction. 1 1/2 means one and a half, which is 3/2. For a negative mixed number put the minus sign in front: -1 1/2.
Can I type a decimal such as 0.75?
Yes. 0.75 is read exactly as 75/100 and simplified to 3/4, so the answer is exact rather than rounded. In Turkish, type 0,75.
Why does dividing by zero give an error?
Dividing is the same as multiplying by the reciprocal of the second number, and 0 has no reciprocal. Change the second number to something other than 0.
Why is there a decimal as well as a fraction?
The fraction is exact: 1/3 stays 1/3. The decimal is rounded, so 1/3 shows as 0.333333. It is given to make the size of the answer easier to read.
Are the numbers I type sent to a server?
No. The calculation runs in your browser, and nothing you type is sent to us.
Does it work with very large numbers?
Yes. The arithmetic uses whole numbers of any size, so long numerators and denominators do not lose any digits.
Sources
- Wikipedia: Fraction (mathematics), addition, mixed numbers and simplifying
- Wikipedia: Greatest common divisor, with Euclid's algorithm
Figures and text last checked on Tuesday, November 10, 2026.