hey guys, on my Dell vostro 3500, above the numeric keys on the right of the keyboard, there are three buttons that i'd like to remap: the 'calculator', the 'CE' and the '+/-' keys.

the calculator key is read by the system as (in italian) "Avvia (1)", translated as something similar to "start (1)", so I'll just assign it a shortcut.
the CE and the +/- key, instead, are read as "canc" and "F9", and i'd like to assign them different name from the other keys: i'd like to assign CE a shortcut to ad application, and to the +/- the special character "±". how can I do this?
(i'm running kubuntu 20.10)