Find the Greatest Common Factor (GCF) or Greatest Common Divisor (GCD) using multiple calculation methods
Enter at least 2 positive integers
GCD(a, b) = GCD(b, a mod b)
Continue until remainder = 0
Most efficient for large numbers
1. Find prime factors of each number
2. Identify common prime factors
3. Take minimum power of each common factor
4. Multiply these together
1. List all factors of each number
2. Find factors common to all numbers
3. Select the largest common factor
Best for small numbers
GCF(a, b) × LCM(a, b) = a × b
GCF(a, 0) = a
GCF(a, 1) = 1
GCF(a, a) = a
The Greatest Common Factor (GCF), also called Greatest Common Divisor (GCD), is the largest positive integer that divides all given numbers without leaving a remainder. For example, GCF(12, 18) = 6 because 6 is the largest number that divides both 12 and 18.