I think that you need to give us more info. What is an instance, what dates
do you hold (every day, every week etc.). It should just be a matter of
incrementing by some index, but therein lies the detail.

--
HTH

Bob Phillips

(replace somewhere in email address with gmail if mailing direct)

"JulieS" wrote in message
...
Hello,

I have created a workbook October 2006 through December 2008, I now need
to
add week numbers to column a, counting backwards, starting on different
days,
for example:

Instance 1
12/2/07 = week 0
11/25/07 = week 1
11/18/07 = week 2

Instance 2
3/2/08 = week 0
2/24/08 = week 1
2/17/08 = week 2

Any help you can offer would be great! I have at least 6 different
instances to add to this one calendar. One thing I should probably add,
the
instances may over lap.

JulieS