Have you tried using the "auto-fill" in Excel?
If you have an entire column of items you put the formula in the first cell, make sure you get the result you desire and then you can do the copy/paste, or use auto fill which is an option that sits on the bottom right corner of the cell.
You go to that corner in the cell and once your cursor changes to a "+", you can double-click on it and it should populate all the way down to the last entry (as long as there are no populated cells, that is).