joemartin Thank you for this solution. I am running Solus 4.1 MATE and it worked. However, I had to make some modifications to what you wrote. If you download and extract the numlockx file (a tar.gz file) from the github URL you gave, and place it in your Downloads folder, then when you extract it there, it creates a folder named numlockx-1.2, NOT numlock-master. So, you must cd to numlockx-1.2.
Then, all the steps worked, EXCEPT the last two: sudo lightdm-settings does not work, it comes back with the message "command not found". Also, you do not need to "go to Settings ->turn on Activate numlock"; in fact, I could not even understand what this means, what Settings are you talking about? But the good news is, the Num Lock now turns on automatically once I have signed on at the login screen. So, it is not on when you login with your password, but it is automatically on after that (if you enter the correct password, of course). Also, since numlockx is now installed, you can go to terminal, and type numlockx ? to see the options. They are on, off, and toggle; and on is the default.
I still think Solus should just make this an option on Keyboard settings, to avoid all this extra hassle.
