Quick start
- Enter two or more positive whole numbers separated by commas, spaces, or semicolons.
- Press Calculate GCF.
- Read the greatest common factor in the result card.
- Review the Euclidean-algorithm style steps, then copy the answer if needed.
GCF vs LCM
GCF looks downward for the largest shared factor. LCM looks upward for the smallest shared multiple. If you are simplifying, use GCF. If you are finding a common denominator, use LCM.
For example, the GCF of 24, 36, and 60 is 12 because 12 divides all three numbers and no larger whole number does.
How the calculation works
The calculator uses the Euclidean algorithm, which repeatedly compares remainders until the shared divisor is found. For more than two numbers, it carries the current GCF through the rest of the list.
A GCF can be 1 when the numbers do not share any larger factor.
Examples from the calculator
12
12
9
History, privacy, and copying
Recent answers stay visible in the page while you work. The history is kept only in the current browser tab and is not sent to a server.
Copy answer copies the expression and result so you can paste it into notes, homework, a message, or another document.