I have no idea how *you* would do so. How would you calculate it if
you weren't using Access?
Different schools have different grading systems (if you mean a Grade
Point Average, the acronym may have other meanings). Please let us
know how your grades are scored and how you want the GPA calculated.
You should also remember the ng is international.
An acronym in one country may mean something entirely different in an other
eg General Practice Australia, Graphic Press Agency etc