I have a place where the value of A2 can be A,B,C,D,E,H,J,K,L,M,S, or null.
Based in the value entered in this cell, I want O2 to take the value of
Z2,Z3,Z4,Z5,Z6,Z7,Z8,Z9,Z10,Z11,Z12, or 0. I need to calculate this for all
row values of the column O. It's too complex for a nested if/then loop, so I
think I need to either insert a custom macro or embed a VB function, however
both of these are things I don't have a lot of experience with. What do I
need to do?

Thanks!