Welcome to Pfxcalc. Type 'help' for more information.
>> help
Pfxcalc is a prefix notation calculator.
Prefix notation, aka Polish notation, is a form of notation for logic,
arithmetic and algebra, like infix and postfix (reverse Polish)
notation.
The expression '+ 3 4' in prefix notation is as valid as '3 + 4' in
infix notation, as well as '3 4 +' in postfix notation.
Every computation starts with entering a command and the result is
printed *and* saved in a variable that can be recalled by entering