Hi


"Max" wrote in message
...
"Arvi Laanemets" wrote:
This assumes there is a single row for every moth,
and always a row for a month, does it?

Yes of course <g, the assumed set up was described
in the response, as always ..

More general solution (dates in column A, values in column
B, headers in row 1, sum is placed outside of data range, p.e. in cell
C2)
=SUMIF(A:A,""&DATE(YEAR(MAX(A:A)),MONTH(MAX(A:A))-11,0),B:B)

Just a thought. The above would return zero if the dates were not "real"
dates.
(A possibility that I had guessed might be the case, in the earlier
response. It wasn't clear from the orig. post.)

P.e. month names as text?
It's simply - then OP will be in trouble :-)

(Of-course even then it's possible, but the formula will be huge. It's main
reason I always advice to use real dates - when there is a need, then you
always can format them to be displayed as month names. But my 1st preference
will be the format "yyyy.mm", which allows to sort data properly.)


--
Arvi Laanemets
( My real mail address: arvil<attarkon.ee )



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Max
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