The grades a, b, c, and d that you may get in a class are discrete. there is no such thing as a grade of b 1/2, for example. however, grade points can be assigned to these grades according to the table shown below: similar to grades, grade points can be sorted. but they can also be added and divided and so on. this allows for the calculation of a grade point average, or gpa. for example, the grade point average of a, a, b+, b, b-, and c+ is(4.0 + 4.0 + 3.3 + 3.0 + 2.7 + 2.3)/5 = 3.22. grade points can take on any numeric values between 0 and 4. they are an example of a variable.