Private Sub Worksheet_Change(ByVal Target As Range)
For c = 2 To 8
If Cells(7, c) = "" Then GoTo suite:
If Cells(2, c) = "" Or Cells(3, c) = "" Or Cells(4, c) = "" Or Cells(5, c) = "" Or Cells(6, c) = "" _
Then GoTo suite:
If Cells(7, c) < 12 Or Cells(7, c) > 20 Then MsgBox "Moyenne en " & Cells(7, c).Address & " n'est pas correcte, refaire les calculs"
suite:
Next
End Sub