I would like to be able to add a tab and have a copy in a set of formulae and have the formula in a cell refer to the same cell locations in the worksheet to its left in the worksheet tabs.

Example: Worksheets (tabs) are Week1, Week2, etc. I want cell A1 in Week 2 to refer to cell A1 in Week1 and perform a simple subtract function. Then When I add in a new worksheet (tab) for Week 3 I want to be able to copy the formulas in the new worksheet and have cell A1 now refer to Week 2 for its function.

How do I get the sheet reference to be relational to a tab rather than an absolute worksheet name?