Get number of "non-sum-zero" columns

Hi,

I have a table which contains numbers. The table has between 1 and 8 columns (and a fixed number of rows). I need to find out how many columns it has. The number of columns is given by the last column which has a sum greater than 0 (or by the column number of the first column with sum equal zero, minus 1).

Does somebody have an idea to do this without VBA, e.g. with LOOKUP(SUM())?

Thanks!!

Thanks, Ace_XL!

I don't want to use helper columns or rows. In the real workbook, there is a worksheet I work on (where the formula goes), and there are plenty of input sheets, which I read but I don't want to change.