I need to create a block numbering scheme, when the blocks do not necessarily
fall one after the other. How would I create a formula for the following:

Look at the value in the cell to the left (in column A, which contains a
concatenation formula-the value will be in the format AA-AA-##), compare that
value with all the other values above it in column A. When I find the first
match (going from the bottom up), stop and look at the adjacent number in
column B and add 1 to it. If there is no match, display the word NEW or leave
blank or even an error would be OK.

I'm using Excel 2003

Thanks in advance for any help I can get.