generating unique reference number

[Rachel]

I have the following set of data

Trust Account Number SI date (SDA booking date) Principal Amount TF
Rate RESULTING VALUES
01 0500247 22-Sep-08 12,000,000.00 0.25% 01 0500247_0001
01 0500324 20-Oct-08 5,000,000.00 0.25% 01 0500324_0001
01 0500340 05-Sep-08 1,000,000.00 0.55% 01 0500340_0001
01 0500340 10-Sep-08 1,000,000.00 0.55% 01 0500340_0002
01 0500340 19-Sep-08 4,000,000.00 0.35% 01 0500340_0003
01 0500340 22-Sep-08 5,000,000.00 0.35% 01 0500340_0004
01 0500340 22-Sep-08 5,000,000.00 0.35% 01 0500340_0005

Can anyone help me in coming up with a code that will generate the resulting
values? Note that columns a-e are inputted manually while column F should be
automatically generated.

THANKS!

 

[Rick Rothstein]

It is kind of hard to tell what data is located in what columns; however,
assuming data you want to add the counter to is located in Column A starting
in Row 2, put this formula in F2 and copy it down...

=A2&"_"&TEXT(COUNTIF(A$2:A2,A2),"0000")

If the data is in Column B, then just change the A's to B's in the formula.