The only difference between most PC keyboards and genuine Apple keyboards (USB connected) is that some keys have to be substituted to get the Apple equivalent such as the Windows key for the command key. You don't have to turn off the numlock on a PC keyboard to use the arrows keys. Everything should work OK. If it doesn't for some reason, that means the PC keyboard is not compatible.
Does your PC keyboard have an Fn key? If it does, holding down the Fn key at the same time as the up arrow acts like a page up, and so on.
The person who owns the computer wants to use the number pad like arrows. If this isn't possible, another keyboard is needed. I'm not looking for work arounds, I'm asking if you can make a PC keyboard use the number pad as arrows.
This is a logitech wired keyboard. When you touch the "num lock" key, the mac makes a "dunk" noise and the number are still in effect. I was looking for guidance as to a setting somewhere else that might allow the keys to be toggled, like in the settings.
I use my Mini with a Windows Keyboard from time to time (a Microsoft Ergonomic keyboard) and mine has the same behaviour.
Interestingly, my keyboard has a Numlock light and I normally have this on. As soon as I plug in to the Mini the Numlock light goes off, the Numlock key doesn't do anything but the keys function as numbers. On a Windows PC, if the light is off the keys would act as cursor keys etc.
So at least you know this appears to be 'normal' behaviour.