I need a number pad with Lenovo x220 laptop and I lack external kbd, for using Blender more on the point 3.10 here and this discussion here. The keyboard with X220 is similar to this one where the middle keys have numbers like a number -pad.

How can I get a number pad working so that they do the typical number-pad-functions in Blender? Look the above number row is not programmed to work like the number pad, I need the real number pad function keys. How?
(Btw I run Ubuntu, W and other OSs so I would like to find some OS -independent solution.)