Negative numbers with exponents in RPN

[Peet]

The easiest way to understand RPN is to imagine how to calculate in your head or you do it on paper.

a) if you want to calculate -2^2 then first you take 2^2 and then you set the "-" sign
in RPN: [2] [X^2] [+/-] and you get -4

b) if you want to calculate (-2)^2 then you have to take -2 an then build the square
in RPN: [2] [+/-] [X^2] and get 4

At RPN, always calculate in the exact order a person would calculate, not as it was written down.

e.g. if you have √(2+2) than you first take the numbers 2 and 2, add them together an than build the square root
in RPN: [2] [enter] [2] [+] [√]