Sub Numéroter()
Dim chn$, lig&: chn = ActiveSheet.Name
If chn = "Feuil1" Then lig = 3 Else _
If chn = "Feuil2" Then lig = 7
If lig = 0 Then Exit Sub
Dim n&: Application.ScreenUpdating = 0
Do
n = n + 1: Cells(lig, 2) = n: lig = lig + 1
Loop Until Cells(lig, 2).Borders(10).LineStyle = -4142
End Sub