Greatest Common Factor Calculator
To use the GCD / GCF / HCF Calculator below just enter a set of numbers separated by commas (,).
Greatest Common Factor Calculator / Converter
Enter values separeted by commas: Ex.: 2,4,8, etc. 
Detailed Answer:Greatest Common Divisor explained here

Use our Greatest Common Factor to find the GCF of any combination of numbers.
See also:
How to find the Greatest Common Factor
GCF example:
The first step is to find all divisors of each number. For instance, let us find the gcf(4,6,8).
In this case we have:
 The factors of 4 (all the whole numbers that can divide the number without a remainder) are 1, 2 and 4;
 The factors of 6 are 1, 2, 3 and 6;
 The factors of 8 are 1, 2, 4 and 8.
The second step is to analyze which are the common divisors. It is not difficult to see that the 'Greatest Common Factor' or 'Divisor' for 4, 6 and 8 is 1. The GCF is the largest common positive integer that divides all the numbers (4,6,8) without a remainder.
The GCF is also known as:
 Greatest common divisor (gcd);
 Highest common factor (hcf);
 Greatest common measure (gcm), or
 Highest common divisor