I have a single workbook consisting of 53 sheets (one per week in the fiscal
year). I have a summary sheet that I need to extract data from the same cell
in every sheet, updated automatically when any sheet is updated.

eg, Each of the 53 worksheets within the workbook has a total (car mileage)
in cell C34, which I need to summarise as a total in a cell on the summary
worksheet, on the basis of cell C34 on Sheet1+Sheet2+Sheet3... +Sheet53.

What function do I need in the required cell on the Summary sheet, please,
to meet my needs?

I can't seem able to do what I want (I'm a bit dumb on Excel beyond basic
and simple boolean logic functions), but I am sure that my problem will be
simple to most of you experts.

My apologies if this has already been covered, and that I failed to find it.

Many thanks and best regards,
Gordon