Just a couple of thoughts.

You didn't need =sum() in your formula.

=A1+C1+E1+G1+...
would have worked ok.
or
=sum(sum(a1,c1,e1,...up to 30 parms),sum(up to 30 parms),sum(up to 30 parms))

=Sum() has the limitation of only accepting 30 parameters. But you can break it
up into pieces.

Both of these formulas are much uglier than the ones suggested by Max.

But they do have the added benefit that if you insert a column, then the
formulas adjust nicely.

The formulas in Max's suggestions will not calculate what you want if you insert
a single column.

I set up a workbook using formulas similar to Max's and when the user inserted
description columns, the calculation wasn't valid any more.

I like to to insert a helper row and just put an indicator in the columns that
should be summed.

For instance, put # in row 1 for every column that should be added.

Then use a formula like:
=SUMIF($A$1:$L$1,"#",A2:L2)
or even
=SUMIF($1:$1,"#",2:2)
for the whole row



Kanga 85 wrote:

I need to sum alternate columns over a very large number of columns. Is
there an easy way to do this? Sum(A1+C1+E1+G1 .... ) seems to bomb out
after about 32 entries and I need more than this.
Any Help,
Thanks,

--

Dave Peterson