In article ,
Roger Govier wrote:

But just copying the respective formulae to A10 and B10, then marking both
cells and dragging the fill handle on B10 across the page achieves the
desired result.
Then mark the range of row 10 and copy down.

Thanks for pointing that out, Roger!

I don't see how the OP can achieve his 52 weeks going across the page though
as he would obviously need 367 columns.

Actually, I completely overlooked this point. It looks like the OP will
have to split it up. However, it's possible that he was already aware
of it. If not, he's aware of it now. :)