OK. I am not sure how adding a formula is more automated than doing a Find/Replace (you can do a Replace All to do them all at one time).
If you truly want something automated, VBA would be the way to go. You could turn on the Macro Recorder and record yourself doing the Find/Replace All, and you would then have the code for that.
Then, you could easily replace them all with a single click (if you attach the macro to a button), or a keyboard shortcut, without having to use any helper columns.