Bdtyktl

Physically remove the NumLock key. When your finger goes to press it, it won't be there.

It's possible to automatically put it back on (within a few milliseconds) when it gets turned off, via an application.

This guy created an autohotkey script for it which he calls "Numlock Enforcer"
http://www.donationcoder.com/forum/index.php?topic=9018.0

Not to most elegant solution, but it should work.

Maybe not the answer you are looking for, but it solved that problem for me:

Activate the sound for the Lock keys in Windows (in Windows 10: Control PanelEase of AccessEase of Access CenterMake the keyboard easier to useTurn on Toggle keys)

That way, when you hit it, it beeps, and you realize it right away. It actually trained me to not hit it anymore at all, because the signal is right when it happens.

The BIOS might have a setting to disable the NumLock key, but we need to know
your computer-model and BIOS-version to discuss this more in depth.
Typically, one boots into the BIOS and looks for an item named
"NumLock State", "Bootup NumLock State" or similar, press Enter
and use the arrow keys to select "Off" or "Disabled", then press Enter.

For Windows hackers, the registry contains in HKCUControl PanelKeyboard
an item named InitialKeyboardIndicators which has the undocumented value
of 1 to disable the NumLock. Its effectiveness may vary according to
the version of Windows.

The brutal solution is to pop off the Numlock key cap and use a pen to change
its setting when required. The setting will normally stick, since
Windows XP and later remember its state across boots
(unless the BIOS or other setting interferes).

Step 1

Change the registry to set initial state of NumLock to on at startup:

HKEY_USERS.DEFAULTControl PanelKeyboardInitialKeyboardIndicators

  Set to Value to 2

Step 2

Add an AutoHotkey script to monitor the key and ensure it cannot be turned off. Install AutoHotkey, and create a new script named MyBestNumlockHack.ahk. Put this script in your C:Users{User Name}AppDataRoamingMicrosoftWindowsStart MenuProgramsStartup directory.

Numlock::

  if (!GetKeyState("NumLock", "T"))

    SetNumLockState, On

  return

Make a timer and call it NumlOn.
Set the interval on 100.

Public Const VK_NUMLOCK = &H90

Declare Function GetKeyState Lib "user32" Alias "GetKeyState" _

(ByVal ByValnVirtKey As Integer) As Short

Dim NLKey as boolean



Private Sub me_keyDown(ByVal sender As System.Object, _

ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

    If e.KeyCode = Keys.NumLock And Not NLKey Then

        If Not GetKeyState(VK_NUMLOCK) Then

            e.Handled = True

            NumlOn.Start()

            Exit Sub

        End If

    End If

End sub



Private Sub NumlOn_Tick(sender As Object, e As EventArgs) _ 

Handles NumlOn.Tick

    NLKey = True

    If Not GetKeyState(VK_NUMLOCK) Then numlockON()

    Application.DoEvents()

    NumlOn.Stop()

    NLKey = False

 End Sub

Forgot a sub...
This is fully working

Public Const VK_NUMLOCK = &H90

Declare Function GetKeyState Lib "user32" Alias "GetKeyState" _

(ByVal ByValnVirtKey As Integer) As Short



Private Sub numlockON()

    keybd_event(VK_NUMLOCK, 0, 0, 0) ' Press NUMLOCK key down

    keybd_event(VK_NUMLOCK, 0, KEYEVENTF_KEYUP, 0)

End Sub



Private Sub me_keyDown(ByVal sender As System.Object, _

ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

    If e.KeyCode = Keys.NumLock And Not NLKey Then

        If Not GetKeyState(VK_NUMLOCK) Then

            e.Handled = True

            NumlOn.Start()

            Exit Sub

        End If

    End If

End sub



Private Sub NumlOn_Tick(sender As Object, e As EventArgs) Handles NumlOn.Tick

    NLKey = True

    If Not GetKeyState(VK_NUMLOCK) Then numlockON()

    Application.DoEvents()

    NumlOn.Stop()

    NLKey = False

End Sub

If you use Autohotkey, you can add the following line to your script:

SetNumLockState, AlwaysOn

Be sure to put this line before your hotkeys. I put it at the very beginning of my script so I make sure it always works fine, if you put it in the middle or at the end of your script, it may not work.