HCF Calculator
Highest Common Factor (GCD) of two or more whole numbers.
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About this calculator
The HCF/GCD is the largest number dividing all inputs exactly — used to simplify fractions (48/180 → 4/15), cut sheets into largest equal squares, and fairly distribute items into groups.
Formula
Euclid's algorithm: HCF(a,b) = HCF(b, a mod b) until remainder 0.
Frequently Asked Questions
HCF of coprime numbers?
Always 1 — e.g., HCF(17, 28) = 1 despite both being composite-friendly in other pairings.
Relation between HCF and LCM?
For exactly two numbers: HCF × LCM = product of the numbers — handy for verification.