How do I put a formula to sum the same cell across a number of she

[New Excel]

I have several files each with about 20 spreadsheets each. For each file I'd
like to put in a formila that adds all the separate sheets together

 

[Frank Kabel]

Hi
do you mean something like
=SUM('sheet1:sheet20'!A1)

 

[Nijan]

Thank you Frank. This is exactly what I required.
Thanks again
Nijan