Ron,
J2: =SUM(INDEX(2:2,1,COLUMN(J2)-6):INDEX(2:2,1,COLUMN(J2)-1)) resolves one
question - thanks again. And experimenting has shown me this can also be
used for columns after J by changing to +6 (or +12) and the -1 to +1. What
does the "other" 1 control?

I also found
=SUM(IF(MOD(COLUMN(G4:V4),2)=1,G4:V4)) which sums alternate columns (thanks
Gord Dibben)
These have been a big help.

But everything leads to another question. Which is:
Can these two be combined so that when I insert two (or N) columns to a
sheet, the rolling 6 month totals which add every other (or nth) column are
automatically updated as described originally?

Thanks again.

Wal50


"Ron Coderre" wrote:

Glad to help....and thanks for the feedback.

***********
Regards,
Ron

XL2002, WinXP


"wal50" wrote:

Thanks Ron. That looks like it does the trick.
WAL50

"Ron Coderre" wrote:

Try something like this:

With values in B2:i2

This formula sums the 6 cells immediately before J2
J2: =SUM(INDEX(2:2,1,COLUMN(J2)-6):INDEX(2:2,1,COLUMN(J2)-1))

If you insert a column before Col_J, the formula, of course, moves into K2
and automatically adjusts so it sums the 6 cells immediately before K2

Is that something you can work with?
***********
Regards,
Ron

XL2002, WinXP


"wal50" wrote:

The sheet calculates 6mo totals and averages. Each month, a new column is
inserted and added to the totals & average, while the one from six months ago
is dropped. (column is retained for other reasons, just no longer included in
these calculations).
Is there a way to do this without having to update the column references for
the calculations every month?
Thanks in advance,
Wal50