GCF Calculator

Find the greatest common factor (and least common multiple) of a list of numbers. Enter them separated by commas.

GCF
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Greatest common factor.

Usage Tip

To add fractions, the LCM of the denominators is the least common denominator; to reduce one, divide top and bottom by the GCF.

THE MATH
The GCF uses the Euclidean algorithm across all numbers.
LCM is found from the same pairs.
The greatest common factor is the largest number dividing every value evenly; it is used to reduce fractions.
The least common multiple is the smallest number all values divide into, used to add fractions.
Enter two or more positive whole numbers separated by commas.
Non-integer or non-positive entries are ignored.
Both the GCF and the LCM are shown.
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