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Greatest Common Factor (GCF) Calculator
Find the greatest common factor (GCD) of two numbers using the Euclidean algorithm.
About This Calculator
The Euclidean algorithm (circa 300 BCE) finds the GCD by repeated division — one of the oldest algorithms in mathematics. GCF is used to simplify fractions: 48/18 simplifies to 8/3 (dividing both by GCF of 6). Cryptography uses extended Euclidean algorithm for modular inverse calculations.