Enter two or more numbers to find their greatest common factor (GCF) and least common multiple (LCM).
What this calculator does
This calculator finds both the greatest common factor and the least common multiple of a list of whole numbers at once. Enter them separated by commas or spaces.
GCF and LCM are staples of fractions, ratios and number theory.
Getting your answer
- Enter two or more whole numbers.
- Read the GCF (largest shared factor).
- Read the LCM (smallest shared multiple).
How the number is calculated
GCF via the Euclidean algorithm
LCM(a, b) = a × b ÷ GCF(a, b)
A worked example
As an example, with a numbers of 12, 18, 24, the calculator returns a GCF of 6. Alongside it, LCM comes out at 72. Change any field and every figure updates as you type.
Common questions
What’s the difference between GCF and LCM?
GCF is the largest number that divides all of them; LCM is the smallest number they all divide into.
Where are they used?
Simplifying fractions uses the GCF; adding fractions with different denominators uses the LCM.
Can I use more than two numbers?
Yes — enter as many as you like and the calculator finds the GCF and LCM of the whole set.