Workbooks or worksheets? Worksheets is possible.
Type =Sum(
Highlight the desired worksheets and select cell A1
Type your closing brackets and you are done with something like...
=SUM(Sheet1:Sheet100!A1)

If you mean workbooks then not there is nothing simple and even if you could
it would be an incredibly brittle formula. If one of the workbooks has
something wrong in A1 then the formula colapses. Worse still if one of the
workbooks gets moved or deleted then the entire formula colapses. If the
formula colapses there is no effective way to debug it especially since it
would be incredibly long...
--
HTH...

Jim Thomlinson


"Neil Pearce" wrote:

Dear all,

Is there a quick formula I can use to add all A1 cells across 100 different
workbooks?


Kind regards,

Neil