Assuming that the source data is already/always in pairs from row2 down, eg:

Detroit 1Pa 06-04-2004
Detroit 1Pa 23-06-2004
Detroit 1Pb 01-08-2004
Detroit 1Pb 05-11-2004
Miami 1Pa 06-04-2004
Miami 1Pa 23-06-2004
Chicago 1Pb 01-08-2004
Chicago 1Pb 05-11-2004
etc

Then perhaps this might suffice in D2, copied down:
=IF(OR(A2="",B2=""),"",IF(MOD(ROW(),2)=1,C2-C1,""))
to return the number of days
between the 2 events on every "2nd event" line
--
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
---
"Sting17" wrote:
Can you reformulate to make it read the first two letter of the pairing code:
"1P" of the "1Pa"? I can have:

Detroit 1Pa 01/01/01
Detroit 1Pb 03/01/01

These would be paired events even thought the letter"a" and "b" are
different. So basiically, it would be everything that was "Detroit" and "1P"
that I would want to apply the calculation to. Possible? Thanks.