Lets assume you have 4 text boxes (columns) to sum. We'll name then Box1,
Box2, Box3, Box4.
Now, this is the easiest way that I know of
In the report footer, add a unbound control under each column. Set it's
visible property to false.
Name them Total1, Total2, Total3, Total4.
Set their control sources to =Sum([Box1]), =Sum([Box2]), etc.
Now, add a 5th unbound control, and set it's control source to =Total1 +
total2 + total3 + total4