GCF and LCM Calculator
Enter two or more whole numbers separated by commas or spaces.
How this calculator works
The greatest common factor (also called HCF or GCD) is the largest number that divides all your numbers exactly. It is found with the Euclidean algorithm. The least common multiple is the smallest number all of them divide into, calculated as a x b / GCF(a, b) and extended across the list.
Frequently asked questions
What is the difference between GCF and HCF?
Nothing. GCF, HCF and GCD all mean the greatest common divisor.
When do I use the LCM?
To add or subtract fractions with different denominators, and to find when repeating events line up.
What is the GCF of two prime numbers?
1, because primes share no factor other than 1.
