By selecting data from a drop-down menu in an Excel spreadsheet, a result elsewhere in the spreadsheet changes. But manually clicking the drop-down button on the cel with the mouse, scrolling to the relevant data, clicking it, then looking back to the changed result is time-consuming and monotanous. Is there a way to "select" the data from the drop-down menu so I can just tap the Down key on my keyboard and go through the data while watching the result change accordingly? This can be done on web-pages that have user history or relevant searches. Surely Excel can do it too.

I don't think you are going to be able to do it with a standard drop down. As I'm sure you know, the cell that is changing is dependent on the cell that contains the choice from the drop down. Simply scrolling or tapping through the list doesn't place the value in the drop down cell, so the dependent cell won't change. There may be other methods as well, but nothing comes to mind right now. You could do it with a list of values in a range of cells by using a Selection_Change macro, but not with a standard drop down.