GCF/GCD Calculator

This calculator finds the Greatest Common Factor of two to four numbers using the Euclidean algorithm (lines 11-38, repeated subtraction of remainders rather than factorization). First Number and Second Number are required; Third Number and Fourth Number default to 0 and are structurally excluded from the working list whenever they're 0 (line 110-111 only adds them when nonzero) — so with the defaults unchanged, the algorithm runs on First Number and Second Number alone, and only folds in a third or fourth value once one of those optional fields is set to something nonzero. GCF is a genuinely chaotic function of its inputs, not a smooth one: at the defaults (48, 36), the GCF is 12, but nudging Second Number by 10% lands on 32 (floor of 32.4) on the low side and 39 (floor of 39.6) on the high side, and GCD(48, 32) is 16 while GCD(48, 39) is only 3 — the GCF actually falls as Second Number rises through this range, the opposite of a "bigger numbers, bigger factor" intuition, because what matters is which prime factors the two numbers happen to share, not their size.

Are Numbers Coprime? (line 190) is simply a check for whether GCF equals exactly 1; it is not computed independently. This calculator does not accept 0 as a meaningful value for any of the four number fields (line 114-115 treats any included 0 as invalid and skips the algorithm entirely), and it floors all inputs to integers (line 103-106) without validating that they're positive.