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Use this free fraction reducer to simplify any fraction to its simplest form. Enter a numerator and denominator, and the simplified fraction calculator shows you the step-by-step process: finding the GCD, dividing both numbers, and confirming the result is fully reduced. It works as a fraction simplifier for proper fractions, improper fractions, mixed numbers, and very large numbers, and it tells you when a fraction is already the simplest fraction it can be.
"Write your answer in simplest form." Every test says it, and barely any textbook explains it. Here is the plain-English version: a fraction is in its simplest form when no number other than 1 divides evenly into both the top and the bottom. That is the whole idea. Some textbooks call it lowest terms or say the fraction is fully reduced; all three phrases mean exactly the same thing.
Check the greatest common divisor (GCD) of the numerator and denominator. If the GCD is 1, you are done. If it is anything larger than 1, there is still reducing to do. A quick shortcut: if both numbers are different primes, the fraction is always already in simplest form. That is why 7/11 needs no work at all, and neither do 5/8, 3/7, or 13/15.
| Fraction | GCD | Divide both by the GCD | Simplest form |
|---|---|---|---|
| 6/8 | 2 | 6 ÷ 2 = 3, 8 ÷ 2 = 4 | 3/4 |
| 10/15 | 5 | 10 ÷ 5 = 2, 15 ÷ 5 = 3 | 2/3 |
| 12/18 | 6 | 12 ÷ 6 = 2, 18 ÷ 6 = 3 | 2/3 |
| 24/36 | 12 | 24 ÷ 12 = 2, 36 ÷ 12 = 3 | 2/3 |
| 48/180 | 12 | 48 ÷ 12 = 4, 180 ÷ 12 = 15 | 4/15 |
| 7/11 | 1 | Nothing to divide | 7/11 |
The number you are looking for is the greatest common divisor, sometimes called the greatest common factor (GCF). It is simply the largest number that goes evenly into both the numerator and the denominator.
For large numbers, listing every factor gets tedious. The Euclidean algorithm is faster: divide the larger number by the smaller, note the remainder, then repeat with the smaller number and that remainder until the remainder is 0. The last non-zero remainder is the GCD. For 48 and 180: 180 ÷ 48 = 3 remainder 36, 48 ÷ 36 = 1 remainder 12, 36 ÷ 12 = 3 remainder 0, so the GCD is 12.
Most wrong answers come from dividing by a common factor instead of the greatest one. Simplify 24/36 by dividing both by 2 and you get 12/18, which looks simpler but is not fully reduced: 12 and 18 still share a factor of 6. Always divide by the GCD. If you did divide by a smaller factor, just repeat the process on the result until the GCD is 1.
Simplifying a fraction means reducing it to its lowest terms, where the numerator and denominator have no common factors other than 1.
Why Simplify Fractions?
Pro Tip:
Always simplify your final answer when working with fractions to ensure you've found the most reduced form.
The GCD is the key to simplifying fractions. It's the largest number that divides both the numerator and denominator evenly.
Methods to Find the GCD:
Pro Tip:
For large numbers, the Euclidean algorithm is much faster than listing all factors!
Once you have the GCD, simplifying a fraction is straightforward.
Step-by-Step Guide:
Remember:
A fraction is fully simplified when the GCD of its numerator and denominator is 1.
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Every one of these has its own page with the full working, the decimal, and the percentage.
These have a greatest common factor of 1, so they cannot be reduced any further.
Common questions about simplifying fractions