Dear Experts!

I want to calculate the points and division of the students scored in 9 subjects but you have to choose only seven subjects that the students has scored mostly. The marks of the students are shown in terms of A,B,C,D and F where A=1,B=2, C=3,D=4 and F=5. how can i do it? if forexample a students scored A,B,B,B,D,C,C,B,D,A. Manually the student has scored points 13 and Division I.