Assuming the values are always stored in column G why don't you add (in any
other empty column) formula as follows:
=IF(NOT(ISBLANK(G1)),CONCATENATE(LEFT(G1,LEN(G1)-1),"2"),"")
The formula shows empty string if there is now value in column G and it also
assumes that the length of string in column G may vary.

Hope it helps.

Kind regards
IgorM

"maryj" wrote in message
...
We are using Excel 2007. We have a large list of id numbers that will need
the last character changed from a 1 to 2. The length of the list will
always
vary but will always be in Column G.

For example:
11323674US01
11321507US01
11378181US01
need to be updated to:
11323674US02