Gail Gurman wrote in
:

I've created an array of grade values:

{"A+","A","A-","B+","B","B-","C+","C","C-","D+","D","D-","F";4.3,4,3.7,
3.3, 3,2.7,2.3,2,1.7,1.3,1,0.7,0.5}
The problem is that when use LOOKUP to look for "C-", I get 2.7 (which
is the value for B-) when I should get 1.7. (I.e., LOOKUP("C-", Array)
returns 2.7, where Array is the array above.)
Can anyone see what is causing this error?

Yet again, I solved my own problem. Turns out the elements in the first row
have to be in ascending order, so they have to be {"A","A-","A+",...}.