The Greatest Common Factor (GCF) for 12 and 64, notation gcf (12,64), is 4.
* Factors of 12 are 1,2,3,4,6,12;
* Factors of 64 are 1,2,4,8,16,32,64.
So, the 'Greatest Common Factor' or 'Divisor' is 4 because it is the greatest number that divides evenly into all of them.
