If you're willing to use a User Defined Function.......

Function PrevSheet(rg As Range)
n = Application.Caller.Parent.Index
If n = 1 Then
PrevSheet = CVErr(xlErrRef)
ElseIf TypeName(Sheets(n - 1)) = "Chart" Then
PrevSheet = CVErr(xlErrNA)
Else
PrevSheet = Sheets(n - 1).Range(rg.Address).Value
End If
End Function

Say you have 52 sheets, sheet1 through sheet52...........sheet names don't
matter.

In sheet1 you have a formula in A10 =SUM(A1:A9)

Select second sheet and SHIFT + Click last sheet

In active sheet A10 enter =SUM(PrevSheet(A10),A1:A9)

Ungroup the sheets.

Each A10 will have the sum of the previous sheet's A10 plus the sum of the
current sheet's A1:A9


Gord Dibben MS Excel MVP


On Thu, 15 Nov 2007 08:46:01 -0800, Schotze's Mom <Schotze's
wrote:

I'm creating an Excel spreadsheet with separate tabs for each week of the
year. I need to have cumulative totals carrying over from one week to the
next through the end of the year. Is it possible to do this?