Convert the letter grades on all the homework assignments you want to average to percentages. Typically, the conversion would be:
A+ = 100 percent
A = 90 percent
B+ = 85 percent
B = 80 percent
C+ = 75 percent
C = 70 percent
D+ = 65 percent
D = 60 percent
Anything below 60 percent would normally be considered a failing grade or F.
Add the percentages together.
Divide the sum by the number of assignments considered. For example, if you added 15 homework assignment scores together, divide the resulting sum from by 15.
Translate the answer, which is a percentage, into a letter grade.