Mathemagician by briac is a fun math game, inspired by the game “24”, where you have to make mental calculation to obtain a target number with only the 4 integers given to you. You can use parenthesis and standard operators (+,-,*,/) to get to the result. The fun part in this cartridge is the calculator which includes a parsing Shunting-yard algorithm to generate and evaluate an RPN expression.

http://www.lexaloffle.com/bbs/?tid=3850