About the lcm & gcf calculator
The greatest common factor is the largest number that divides every number in a list; the least common multiple is the smallest number every one divides into. They’re essential for simplifying and adding fractions.
How to use this calculator
- Enter two or more whole numbers.
- Read the GCF and LCM.
Worked examples
- GCF(12, 18) = 6; GCF(6, 30) = 6
- LCM(12, 18) = 36; LCM(36, 30) = 180
GCF 6, LCM 180.
Measurement guidance
Using it with fractions
Divide the numerator and denominator by their GCF to simplify; use the LCM of denominators as a common denominator when adding.
Frequently asked questions
Is GCF the same as GCD?
Yes. Greatest common factor and greatest common divisor mean the same thing.
What if the GCF is 1?
The numbers are co-prime — they share no factor other than 1, and their LCM is their product.