Sub Demo()
Application.ScreenUpdating = False
Dim i As Long, j As Long
i = 1: j = i
With ActiveDocument.Range
  With .Find
    .ClearFormatting
    .Replacement.ClearFormatting
    .Text = "^13[0-9]@^13"
    .Replacement.Text = ""
    .Forward = True
    .Wrap = wdFindStop
    .Format = False
    .MatchWildcards = True
    .Execute
  End With
  Do While .Find.Found
    .Start = .Start + 1
    .End = .End - 1
    If .Text <> j Then .Text = j
    j = j + 1
    .Collapse wdCollapseEnd
    .Find.Execute
  Loop
End With
Application.ScreenUpdating = True
MsgBox j - i & " page #s validated."
End Sub