xandreasx,
Is this issue occurring with the numeric keypad, or the numbers below your Function keys? We ask because the Num Lock key locks the function of the numeric keypad on the keyboard, and disabling it may resolve this.
If you have a separate numeric keypad on your keyboard, the Num Lock key is located in the numeric keypad. If your keyboard has a separate keypad but no Num Lock key, try pressing Shift-Delete.
- If the numeric keypad still doesn’t work as you expect, you may have enabled Mouse Keys, which lets you move the pointer with the keypad.
- To see the option that turns off Mouse Keys, choose Apple menu > System Preferences, click Accessibility , click Pointer Control, then click Alternate Control Methods."
These details are located in If a numeric keypad doesn’t work on Mac
There are some additional features that may change or disable the function of certain keys as well. Check out the "If other keys don’t work" section of If your Mac doesn’t respond to key presses for additional steps to complete.
We look forward to hearing the results.
Regards.