Sub test_II()
Dim i&
i = 6
With Sheets("Suivi")
Worksheets(1).Cells(1, "E").Formula = "=Suivi!" & .Cells(3, i).Address & "+Suivi!" & .Cells(4, i).Address
End With
End Sub
Sub test_III()
Dim i&, f As Worksheet: Set f = Sheets("Suivi")
i = 6
Worksheets(1).Cells(2, "E") = f.Cells(3, i) + f.Cells(4, i)
End Sub
Sub test_IV()
Dim i&, R As Range, X$
i = 6
Set R = Sheets("Suivi").Cells(3, i).Resize(2): X = R.Parent.Name & "!" & R.Address
Worksheets(1).Cells(4, 5) = "=SUM(" & X & ")"
End Sub