gcf is the greatest common factor..
for example, you get the gcf of 6 and 18
first thing to do is get the factors of each
6 = 1,2,3,6
18= 1,2,3,6,9,18
their common factors are.. 1,2,3, 6 .. but remember youre looking for the GREATEST common factor .. and that is 6
the gcf of 6 and 18 is 6
