If you decide to spill the results, you can then use the spilled range operator (#) to perform a calculation on the spilled range. Simply reference the first cell of the spilled range with a # ...
Laptops are practical because you can take them with you. However, laptops have a relatively small screen. If you work on a mobile computer, it quickly becomes annoying to constantly switch programs.
In most counting scenarios in Excel, COUNTBLANK reliably counts blank cells, and COUNTA reliably counts populated cells.