define questions

[DrD]

This works on my emulator:

[Shift][Define] (Name) inc2 (Function) X+2 (and uppercase Variable X is checked). [OK]

Then: (At the command entry line):

(In your case) N:=2, and inc2(N) ==> 4

Case matters! In general, UPPERCASE is used for HOME content, and lowercase is used for CAS content. If you are just getting started with hp Prime, you are likely to be disillusioned by jumping to conclusions, such as Define being worthless. A jet aircraft is worthless, by that standard, if you are asked to fly one without any training or experience.