Some users will find that no matter what value is set in the computer BIOS, num lock will not be enabled automatically on the logon screen. If you are a desktop user and have a number in your password or use a PIN to login to your account, having number lock enabled on the number pad is essential for a speedy logon.
Enabling num lock on the logon screen is a simple registry tweak. In fact, you can just download and import this registry file and then reboot.
If you want to get your hands dirty, open up registry editor and browse to HKEY_USERS\.DEFAULT\Control Panel\Keyboard.
Then edit the value of InitialKeyboardIndicators and set it to a value of 2.