On Thu, 31 Dec 2009 11:20:11 -0800, joseph jordan wrote:

I am trying to create a formula that will automatically sum the last twelve months of data when new months are added (in columns) to the right of the most recent month. Also, don't want to use the "now" feature as information generally lags real time by a couple of months.


Months are columns and the item I want to sum is in the row below the column heading.

Any help would be appreciated.


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Assuming that your data are on row 2 and that the cell next to the
data you want to sum is blank, try this formula:

=SUM(OFFSET(A2,,MIN(IF(ISBLANK(A2:IV2),COLUMN(A:IV )))-13,,12))

Note: This is an array formula that has to be confirmed by
CTRL+SHIFT+ENTER rather than just ENTER.

Hope this helps / Lars-Åke