Public Sub X1()
    Dim rng As Range
    Dim avarItems As Variant
    Dim intI As Integer
    
    Set rng = Range("A1:A4")
    avarItems = rng
    
    For intI =  1  To UBound(avarItems,  1 )
        avarItems(intI,  1 ) = avarItems(intI,  1 ) /  1000 
    Next intI
        
    rng = avarItems
End Sub

Public Sub X2()
    Dim cel As Range
    
    On Error Resume Next
    
    For Each cel In Selection
        If cel.Value <> "" Then
            cel.Value = cel.Value /  1000 
        End If
    Next cel
End Sub