Originally Posted By: joemikeb
My recollection using RPN on an HP calculator the actual keystrokes would be
3 enter 4 + 2 x

Explanation:
  • The reason for pressing "enter" between the 3 and the 4 is to tell the computer that 3 is one entry on the stack and 4 another.
  • The + operator following the 4 serves the same purpose as well as signaling an add operation.
  • Since an operation has been performed the 2 is the taken as a new data entry on the stack and like the 4 is terminated by the x operator (x).

2 enter 3 enter 4 + x would also work, but it takes an additional keystroke and to me is less intuitive than the first version.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein