Const xA = 16598013
 Const xC = 12820163
 Const xM = 16777216
 Const xI = 602453
 Dim Seed As Long
 
 Private Sub Form_Load()
     Seed = 327680
 End Sub
 
 'simule la Fonction Rnd()
 Private Function Random() As Single
     Dim s As Long
     Dim x As Currency
     x = CCur(xA) * Seed + xC
     Seed = x - Int(x / xM) * xM
     Random = Seed / xM
 End Function
 
 'calcul le seed pour la valeur suivante
 Private Sub CalculSeed(r As Single)
     Seed = CCur(xM) * r
 End Sub
 
 'calcul le seed précédent
 Private Sub SeedPrecedent(s As Long)
     Dim x As Currency
     x = (s - xC) * CCur(xI)
     Seed = x - Int(x / xM) * xM
 End Sub
 
 'cherche la valeur correspondant à un seed
 Private Function ChercheSeed(s As Long) As Long
     Dim i As Long
     For i = 1 To 24143031
         Rnd -i
         CalculSeed Rnd
         SeedPrecedent Seed
         If Seed = s Then
            ChercheSeed = i
            Exit For
            End If
         If i And &H1FFFF Then DoEvents
         Next
     Beep
 End Function
 
 '//exemples d'utilisation:
 
 '//retrouve les valeurs initiales de la fonction Rnd()
 Private Sub Command1_Click()
     Dim i As Integer
     For i = 1 To 10
         MsgBox Random & vbCrLf & Rnd
         Next
 End Sub
 
 '//après un Randomize il faut recalculer le seed
 Private Sub Command2_Click()
     Randomize Timer
     CalculSeed Rnd
     MsgBox Random & vbCrLf & Rnd
 End Sub
 
 '//retrouve les valeurs dans l'ordre inverse
 Private Sub Command3_Click()
     Dim i     As Integer
     Dim r(10) As Single
     
     Randomize Timer
     For i = 1 To 10
         r(i) = Rnd
         Next
         
     CalculSeed Rnd
     SeedPrecedent Seed
     For i = 10 To 1 Step -1
         SeedPrecedent Seed
         MsgBox Random & vbCrLf & r(i)
         SeedPrecedent Seed
         Next
     CalculSeed Rnd
 
 End Sub
 
 '//initialise Rnd() avec un seed particulier
 Private Sub Command4_Click()
     Dim s As Long
     Dim R As Long
 
     s = 123456
     R = ChercheSeed(s)
     If R > 0 Then
        SeedPrecedent s
        MsgBox Random & vbCrLf & Rnd(-R)
        Rnd -R
        Seed = s
        MsgBox Random & vbCrLf & Rnd
        End If
 
 End Sub