What is GCF?
The Greatest Common Factor (GCF), or Greatest Common Divisor (GCD), is the largest integer that divides all given numbers without a remainder.
GCF(a, b) — Euclidean algorithm: GCF(a,b) = GCF(b, a mod b) until b = 0
Example
GCF of 48 and 36
GCF(48, 36): 48 = 1×36 + 12 → GCF(36,12): 36 = 3×12 + 0 → GCF = 12