GCF Calculator
Find the greatest common factor of a set of numbers, also called the greatest common divisor or highest common factor. Every step of Euclid's algorithm is shown, along with the prime factorisation and the complete list of shared divisors.
How to Use
Enter two or more whole numbers. The greatest common factor is the largest number that divides all of them exactly — the number you would cancel by when simplifying a fraction or a ratio.
- Two or more numbers at once
- Euclid's algorithm shown step by step
- Prime factorisation of each number
- Every common divisor listed
- Least common multiple reported too
Three ways to find it
Listing factors works for small numbers. Prime factorisation takes the lowest power of each shared prime. Euclid's algorithm is the fastest: it repeatedly replaces the larger number with the remainder of dividing by the smaller, until the remainder is zero. All three agree, and this tool shows the first two plus the full trace of the third.
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