This is a calculator which uses Reverse Polish Notation, or RPN. A full write-up in Japanese (Google Translate link) carries an impressive level of detail about the project, but in short ...

The kids may have colour TFTs and graphing functions, but your keyboard has no equals sign, and that means something. Unfortunately for RPN enthusiasts, the RPN calculator is a little on the rare ...

The team also agreed that any modes with a severity of 2 or less would be accepted and no action required. Following a ...