Sub Macro1()
Dim i
Dim j
Dim derligneA
Dim derligneB
Dim pos
pos = 2
derligneA = Range("A65535").End(xlUp).Row
derligneB = Range("B65535").End(xlUp).Row
For i = 2 To derligneA
For j = 2 To derligneB
Range("E" & pos).Value = Range("a" & i).Value & "." & Range("b" & j).Value
pos = pos + 1
Next j
Next i
End Sub