negative number raised to even power

[Dirk.]

I think at the moment you are missing a very important point in your dicussion:

The prime is a pocket calulator having a (+/-)-key (Or CHS-key if you like). Therefore it pressing (-)(2) is different from pressing (CHS)(2) (== (2)(CHS)).

You don't have this in EXCEL or in other PC-Programms. (But luckily the Prime has a long and a short minus sign so distinguish subtraction from negative numbers)

... as said before: Some other calculators respect this difference in a very smart way, they even make clear what will happen by adding "0-" or even brackets.