RPN Calculator

Adds an RPN calculator as a browser action button.

This extension adds a convenient reverse Polish notation (RPN) calculator as a browser action button. Also called postfix, RPN calculators take their operators after the operands. For example, to get the sum of two and three on a normal calculator, you would hit "2 + 3 =". On an RPN calculator, you would hit "2 Enter 3 +". In general, RPN calculators require fewer keystrokes over a series of extended operations. It may seem strange at first, but once you get used to it, you'll never go back. HP made a series of extremely popular RPN calculators back in the 1970's and 1980's Known Issues: 1) Calculator doesn't automatically get focus when displayed. 2) Keyboard only. Clicking on keys and commands doesn't work.