If it's the whole column you want the total for you can use:

=SUM('Tab 1'!I:I)

"Brian" wrote:

I have to build a workbook where columns of data will be cut and pasted into
Tab 1, then the column totals need to appear automatically on Tab 2. The
problem is that the number of rows of data in Tab 1 will be variable and
unpredictable, although the columns will always start in a known row.

I might be able to do it by something like

=SUM('Tab 1'!I7:I65535)

but is there a more precise way?