I have an Excel file with four worksheets. In each worksheet is a
list of computer names which can total 1,000 per worksheet. I want
to create a new worksheet that lists just four numbers: the total
number of computers/lines in each worksheet. Is that something I can
do with a function?

I'm hoping that as each worksheet gets updated, the "report" worksheet
will automatically update its numbers with the new totals in the other
four worksheets.