Number of Weeks

Hi Guys,

Just created an script and get the week number of  posteddatetime.

upon comparing to my excel data the derived result is not the same.

what is the difference? please advise. thanks.

declare @postedDatetime datetime
Set @postedDatetime='2013/03/27'
Select DATEPART (dw,@postedDatetime) as TWeek
result = 4 
In Excel formula
=ROUNDUP((DAY(O2)+WEEKDAY(DATE(YEAR(O2),MONTH(O2),0)))/7,0)
result= 5