Function REGLE3(number1, number2, numberchoice)
If Not (IsNumeric(number1) And IsNumeric(numberchoice) And IsNumeric(number2)) Then REGLE3 = "Err String": Exit Function
If Val(number2) = 0 Then REGLE3 = "Err Div0": Exit Function
REGLE3 = number1 * numberchoice / number2 'Pas de factorisation inutile
End Function
Sub test()
Debug.Print REGLE3(10, 100, 50), REGLE3(10, 0, 50), REGLE3("A", 10, 50)
End Sub