Reverse Polish Notation Calculator
This interactive online RPN calculator is meant to help you understand how RPN works in a calculator by illustrating how easy it is to use a stack to implement RPN. You can also download the Java source code here that has an RPN parser method. (Note the source code does not construct the front end of a scientific calculator, which is the easy part; instead, the code supports RPN parsing and also converting infix to postfix, the 2 more challenging parts of making a scientific calculator that supports the order of operations)

