Option Explicit
Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
Dim N As Single
If Application.Intersect(Target, Union(Range('A1:B2'), Range('C3:D4'), Range('A8'))) Is Nothing Then Exit Sub
Cancel = True
Select Case Target.Address(0, 0)
Case 'A8'
N = Application.InputBox('Entrez un nombre :', 'Incrémentation', 10, Type:=1)
Target.Value = Target.Value + N
Case Else
Target.Value = Target.Value + 1
End Select
End Sub