Auto number w/ different letter-number combos in same column
 

I have a numbering system that differs for the entry depending on if it is a
manufacturer "M", distributor "D" or retailer "R". All of the reference
numbers are in one column. For example, if column C has each company's name
in it, column B may look like:

M1
R1
R2
R3
M2

etcetera.

I would like to figure out how to autonumber these such that if R2 was
deleted, for example, then R3 would automatically become R2. Is there any
way to do this in one column, since the numbering is not sequential because
Ms, Ds, and Rs are all mixed together? Thanks!!

Colleen B

If you can settle for 2 Col, try this:
In the first Col enter the letter alone
In the second Col enter this formula
=A2&COUNTIF(INDIRECT("a"&ROW()&":"&"a1"),A2)
change the addresses as needed
Ilan

Thanks--that worked perfectly!!!