I am looking for a function that can add up cells across multiple
sheets

I could of course do =Sheet1!A1+Sheet2!A1 etc etc. Problem is that I
have 52 sheets each named after a week end date

My values are all in relative positions and I am looking to add these
up in a sheet called "Summary Report". I add a new sheet each week, so
in effect I'm looking for a formula that will add up all A1 values in
each sheet of the workbook expect anything in "Summary Report". Is
this possible?

Thanks