tony,
Here's the reference page for "Keyboard shortcuts in Premiere Pro":
https://helpx.adobe.com/premiere-pro/using/keyboard-shortcuts.html
It includes this note: "The operating system reserves some commands. You cannot reassign those commands to Premiere Pro. Also, you cannot assign the plus (+) and minus (-) keys on the numeric keypad because they are necessary for entering relative timecode values. You can assign the minus (–) key on the main keyboard, however."
I never remember this. But in the Edit -> Keyboard Shortcuts, there are several Presets, going back to CS6. None of them use the keypad commands. I find that I CAN assign them with a modifier (e.g. I can assign Ctrl+keypad 1). But it won't assign plain keypad 1.
Stan