This what I would do, insert 2 dummy sheets, one after the summary sheet but
before the monthly sheets you add,
the another dummy last, let's call them First and Last, now when you add a
sheet insert it in-between these sheets and since they are empty they won't
affect the totals

=SUM(First:Last!A1:A25)

will sum A1:A25 in all sheets from First to Last and if you put in a March
2006 sheet in there it will also be included,
all sheets that you put in-between these 2 sheets will be totaled

--
Regards,

Peo Sjoblom

Portland, Oregon




"YvonneAsthma" wrote in message
...
I have a 12mth workbook. The first Sheet is the summary page, followed by
an
individual sheet for each month. Monthly data is inputted into the
appropriate month and I want the summary sheet to automatically update the
figures. I currently manually add up each monthly figure to obtain a
cumulative figure.

Program is Excel 2000