noel,

I think validation and a drop down might be your best bet here. Or an
event macro using VBA that changes your input after leaving the cell.

Unless of course the input is in one cell and the desired output is in a
different cell...

Beege

noel wrote:
How do a write a forumla so that is the input is a letter, then look up
values in a table. If the input is a number, than just accept the number.

example:
Table:
a=1
b=2
c=3
Formula;
if input = a, then look up the value of a in a table, which is 1
if input =9, then just keep the input 9 as the result