How this calculator works
Find the greatest common divisor of the numerator and denominator and divide both by it. A mixed number is converted to an improper fraction first. A decimal or percent is expressed as an exact integer pair before reduction. The denominator is kept positive and a zero numerator becomes zero. This same process is also called reducing a fraction to its lowest terms.
Formula
g = gcd(|n|,|d|); reduced pair = (n/g, d/g), with the sign moved to the numerator.
Worked example
42/56 has common factor 14, giving 3/4. The mixed number -2 4/6 is -16/6, which reduces by 2 to -8/3 or -2 2/3.
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Frequently asked questions
Are lowest terms and simplest form different?
They refer to the same reduction: the numerator and denominator share no factor greater than one.
Does reduction change the value?
No. Dividing both parts by the same non-zero factor preserves the fraction's value.
Can I enter a repeating decimal?
Enter its exact fraction, such as 1/3. A finite decimal such as 0.333 is interpreted exactly as 333/1000.