ScanSpotFraction Calculator
The answer is exact, and the working is on screen so you can check it.
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🧮 Fraction Calculator
Add, subtract, multiply or divide fractions and mixed numbers. The answer is exact and reduced, the working is on screen, and nothing leaves the browser.
Fractions are the part of arithmetic most people leave school half-remembering: the rules are short, but a wrong step looks exactly like a right one. This calculator keeps every number as a whole number, reduces the result instead of rounding it, and writes the working out — so the answer can be checked rather than taken on trust.
How to use the Fraction Calculator
- Type the first fraction: whole number on the left (leave it empty for a proper fraction), numerator above the line, denominator below.
- Choose the operator, then fill in the second fraction. Mixed numbers work the same way — 1 1/2 is a 1 with a 1 over a 2.
- The answer updates as you type: the reduced fraction, a mixed number where there is one, the decimal, and the steps that got there.
Why people use it
- Exact, not approximate. The arithmetic stays in whole numbers and only turns into a decimal at the very end, so 1/3 + 1/3 is 2/3 — not 0.6666666666666666 with a rounding decision attached.
- The working is visible. A common denominator is where most mistakes happen; seeing 3/4 + 2/3 rewritten as 9/12 + 8/12 makes that step checkable instead of something you have to believe.
- It refuses rather than guesses. A zero denominator, a division by zero, or numbers too large to stay exact each produce a sentence saying so. A quietly wrong answer is worse than no answer, especially when the result is going into homework, a recipe or a quotation.
Frequently asked questions
Why are there two answers?
The first form is the reduced fraction (17/12). When the numerator ends up larger than the denominator there is also a mixed number (1 5/12). Both are the same value; which one is useful depends on whether your next step is more fractions or a measurement.
How do I enter a negative fraction?
Put the minus on the whole part: -1 1/2 means minus one and a half, not minus a half. With no whole part, the minus can go on the numerator (-3/4) or the denominator (3/-4) — this calculator reads both as the same number.
Can it simplify a fraction I already have?
Yes. Enter it as the first fraction and divide by 1: 12/18 divided by 1/1 comes back as 2/3, with the reduction shown in the working.
Why does it say the numbers are too large?
The tool promises exact answers, and past roughly 10^12 an intermediate product stops being exactly representable as a whole number in JavaScript. Rounding silently would break that promise, so it says so instead. Keep each part under a million and there is plenty of room.