HP 27 funktionalität https://en.wikipedia.org/wiki/HP-27
Lokal als Binary als CLI + GUI und als App (JavaScript)
------------------------- | -0.12345678901234e-12 | ------------------------- | % | 1/x | f | g | ------------------------- | x/y | r\| | STO | RCL | ------------------------- | ENTER | EEX | CLx | ------------------------- | 7 | 8 | 9 | / | ------------------------- | 4 | 5 | 6 | X | ------------------------- | 1 | 2 | 3 | - | ------------------------- | 0 | . | CSH | + | -------------------------