Does This Count As Doing Work?

To avoid thinking about the content of my courses, I started to set up my grade spreadsheet in Excel. Sure, one could use a bunch of nested IF() functions to assign letter grades, but this is a much more elegant solution, don't you think? (And, yes, my school has a quirky system for letter grades.) (Cell B2 holds the student's average, out of 100 points.)

=IF(B2>=70, CONCATENATE(CHAR(74-INT(MIN(90, B2)/10)), CHAR(32 + 11*INT(MOD(ROUNDDOWN(MIN(90, B2),0),10)/5))), IF(B2>=65, "D","F"))