In [115]: d=datetime.datetime(2011, 2, 28)In [116]: (d.day-1)//7+1Out[116]: 4In [117]: d=datetime.datetime(2011, 8, 29)In [118]: (d.day-1)//7+1Out[118]: 5

In [115]: d=datetime.datetime(2011, 2, 28)In [116]: (d.day-1)//7+1Out[116]: 4In [117]: d=datetime.datetime(2011, 8, 29)In [118]: (d.day-1)//7+1Out[118]: 5