numSemaine = DatePart("ww", Now())
Sub test()
Dim madate As Date
madate = Range("A1").value
Range("B1").value = DatePart("ww", madate)
End Sub
For n = 1 To Range("A65536").End(xlUp).Row
Range("A" & n).NumberFormat = DatePart("ww", Range("A" & n), 2)
Next n