I am currently working on a spreadsheet in google sheets and would like to assign negative numbers a letter grade. For example -10 and lower would be graded an F. I used a similar formula to calculate for positive numbers. However when the values are changed to negatives I receive an #ERROR. Any help is appreciated!
=VLOOKUP(AH9,{-10,"F";-5,"D-";-4,"D";-3,"D+";-1,"C-";0,"C";1,"C+";3,"B-";4,"B";5,"B+"7,"A-";8,"A";10,"A+"},2)