Originally Posted by Saxfiend

I think that you have credits and quality points confused.
Typically, the credits earned for an A are the same as the credits earned for a C... meanwhile a C is typically worth 2 quality points, and an A worth 4. You multiply your quality points for each class by the number of credits for the class... do this for each class and add the sums together. Then divide by the total number of credits attempted to calculate your GPA.