Sub Demo()
Application.ScreenUpdating = False
Dim i As Long
i = 0
With ActiveDocument.Range
  With .Find
    .ClearFormatting
    .Replacement.ClearFormatting
    .Text = "[0-9]@>"
    .Font.Superscript = True
    .Replacement.Text = ""
    .Format = True
    .Forward = True
    .Wrap = wdFindStop
    .MatchWildcards = True
    .Execute
  End With
  Do While .Find.Found
    .Text = i
    i = i + 1
    .Collapse wdCollapseEnd
    .Find.Execute
  Loop
End With
Application.ScreenUpdating = True
End Sub