Bonjour,
à tester,
Sub Exposant()
Dim n As Integer, i As Long, y As Integer
For i = 1 To 5 'adapter au nombre de ligne de la colonne A
n = Range("A" & i).Characters.Count
For y = 1 To n
If Mid(Range("A" & i), y, 1) >= 1 And Mid(Range("A" & i), y, 1) <= 4 Then
Range("A" & i).Characters(y, 1).Font.Superscript = True
End If
Next
Next
End Sub