Excel should provide an option to extend a function entered into the first
cell in a column to the rest of the column. For example, say you have a
column of five thousand text codes (A1 to A5000), each of which you want to
truncate by two characters, you should be able to enter the formula for the
first cell (B1) and opt for it to extend to B5000. Obviously you would not
want it to extend further than that though.