Reverse Polish Notation (RPN) is a math notation in which each operator follows its two operands. I own an HP 48G calculator which uses RPN, and when I tried to use the windows calculator I had so much trouble that I wrote my own calculator. Basically, it has a stack of numbers; any time an operator is pressed, that operation is carried out immediately on the two items on the bottom of the stack, or the stack and the input if there is anything in the input. This method reduces the requirements for parenthesis and makes calculating equations/functions relatively easy: instead of (sqrt(5+8))/(8*9) you would enter 5 ENTER 8 + SQRT 8 ENTER 9 * / Practical implications Suggestions/advice/criticisms are greatly appreciated! calc2.au3