Hacer que solo se puedan poner números en muchos textbox

Hay que crear una clase.

Instrucciones para crear una clase
1. Abre tu hoja de excel
2. Para abrir Vba-macros y poder pegar la macro, Presiona Alt + F11
3. En el menú elige Insertar / Módulo de clase
4. En el panel del lado derecho copia la macro

Option Explicit
Public WithEvents tbxCustom1 As MSForms.TextBox 'Custom Textbox
'Referencia
'http://www.ozgrid.com/forum/showthread.php?t=80631
Private Sub tbxCustom1_Change()
     'Message Box To Display Which Textbox Was Changed
    'MsgBox "You added A Number To: " & tbxCustom1.Name
     'This is just to show you can handle multiple events of the textbox
End Sub
Private Sub tbxCustom1_KeyPress(ByVal KeyAscii As MSForms.ReturnInteger)
Dim n As Integer
     'Allow only Numbers To be Entered Into Textbox
    n = KeyAscii
    Select Case KeyAscii
    Case 46 To 57 'números (./0123456789)
    Case Else
        KeyAscii = 0
    End Select
End Sub
Private Sub Class_Terminate()
     'Destroy The Class Object And Free Up Memory
    Set tbxCustom1 = Nothing
End Sub

Ahora en tu formulario copia esto

Dim colTbxs As Collection 'Collection Of Custom Textboxes
Private Sub UserForm_Initialize()
    Dim ctlLoop As MSForms.Control
    Dim clsObject As clsObjHandler
     'Create New Collection To Store Custom Textboxes
    Set colTbxs = New Collection
     'Loop Through Controls On Userform
    For Each ctlLoop In Me.Controls
         'Check If Control Is A Textbox
        If TypeOf ctlLoop Is MSForms.TextBox Then
             'Create A New Instance Of The Event Handler CLass
            Set clsObject = New clsObjHandler
             'Set The New Instance To Handle The Events Of Our Textbox
            Set clsObject.tbxCustom1 = ctlLoop
             'Add The Event Handler To Our Collection
            colTbxs.Add clsObject
        End If
    Next ctlLoop
End Sub
Private Sub UserForm_Terminate()
     'Destroy The Collection To Free Memory
    Set colTbxs = Nothing
End Sub

Saludos.DAM

Si es lo que necesitas.

Me faltó un detalle, En tu formulario copia este código

Dim colTbxs As Collection 'Collection Of Custom Textboxes
Private Sub UserForm_Initialize()
    Dim ctlLoop As MSForms.Control
    Dim clsObject As clase1
     'Create New Collection To Store Custom Textboxes
    Set colTbxs = New Collection
     'Loop Through Controls On Userform
    For Each ctlLoop In Me.Controls
         'Check If Control Is A Textbox
        If TypeOf ctlLoop Is MSForms.TextBox Then
             'Create A New Instance Of The Event Handler CLass
            Set clsObject = New clase1
             'Set The New Instance To Handle The Events Of Our Textbox
            Set clsObject.tbxCustom1 = ctlLoop
             'Add The Event Handler To Our Collection
            colTbxs.Add clsObject
        End If
    Next ctlLoop
End Sub
Private Sub UserForm_Terminate()
     'Destroy The Collection To Free Memory
    Set colTbxs = Nothing
End Sub

Saludos.DAM
No olvides finalizar la pregunta.

Hola.!! Desde ya gracias por responder.

Ahora, copie tal cual me indicaste el código y no funciona, tira un error:

" No se ha definido el tipo definido por el usuario."

Agradezco tu colaboración.

Slds.