How it works
The GCF (also called GCD or HCF) is the largest number that divides all the numbers exactly. The calculator finds it with Euclid's algorithm: repeatedly replace the larger number with the remainder of dividing it by the smaller.
LCM(a, b) = a × b ÷ GCF(a, b)
GCF is used to simplify fractions; LCM gives the lowest common denominator when adding fractions.