bonjour,
une solution via une macro événementielle
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Count > 1 Then Exit Sub
If Target.Column > 3 Then Exit Sub
For i = 1 To 3
If Cells(Target.Row, i) = "" Then c = c + 2 ^ (i - 1)
Next i
Application.EnableEvents = False
Select Case c
Case 1
Cells(Target.Row, 1) = Cells(Target.Row, 2) * Cells(Target.Row, 3)
Case 2
Cells(Target.Row, 2) = Cells(Target.Row, 1) / Cells(Target.Row, 3)
Case 4
Cells(Target.Row, 3) = Cells(Target.Row, 1) / Cells(Target.Row, 2)
End Select
Application.EnableEvents = True
End Sub