This is a calculator app using Reversed Polish Notation (RPN) In Portrait mode, this app provides a basic calculator with the four arithmetic disciplines +, -, x, and /. In Landscape mode, 30 extra buttons are available providing most functions found on a scientific calculator. You can do trigonometry, logarithms, roots, probability, and more. RPN is neat because you can do fancy calculations without having to worry about parenthesis. Putting the operator after the operands allow the operator to infer which are its operands without the clarification offered by paranthesis. The built-in help function (?) provides a short description of each function. The settings page allows you to set the number format, number of decimals displayed, decimal separator and more.