I am attempting to put together a worksheet that tallys this weeks hours with next weeks hours etc.

I need to know how I can total week one and add it to a grand total so that when I put in week 2 it automatically adds to the grand total?

Example:

Qty Hours Total to date Qty Total to date Hours

Then next week I clear out the Qty Hours columns and refill them with new totals but have the total to date columns keep up with the qtys for months at a time?