Some news:I have at least tried to reinstall Linuxmint 20.1 on an ASUS Zenbook 14 UX425J and this time, I succeeded with the problem of the Numpad in the touchpad : it works very well with the F8 touch ( not with the specific zone in the upper right corner or the touchpad, but no matter).
Thanks to everyone who helped me, you are great ! I am very happy and the owner or the PC too. One more convinced user of Linux but she needed absolutely this Numpad for his job.
Some news:I have at least tried to reinstall Linuxmint 20.1 on an ASUS Zenbook 14 UX425J and this time, I succeeded with the problem of the Numpad in the touchpad : it works very well with the F8 touch ( not with the specific zone in the upper right corner or the touchpad, but no matter).
Thanks to everyone who helped me, you are great ! I am very happy and the owner or the PC too. One more convinced user of Linux but she needed absolutely this Numpad for his job.
Franck