Algodoo

Visualisation of an RPN Calculator.

RPN is arithmetic where you enter the numbers and symbols in a different order than usual.
The advantage is that you do not need to enter brackets to force the calculation sequence.

The heart of the calculator is a stack of numbers (here shown as a mechanical device). You
enter the numbers. When you enter an operation symbol (such as +) the caculator takes
two numbers off the stack, operates on them (eg adds them together) and puts the answer
back on the stack (and displays it). TRY IT!