Calculate week number in SharePoint

Add a calculated field column and use this formula:

 

=INT((Created-DATE(YEAR(Created-WEEKDAY(Created-1)+4),1,3)+WEEKDAY(DATE(YEAR(Created-WEEKDAY(Created-1)+4),1,3))+5)/7)

 

I have seen sites that use this formula:

=INT(([datecolumn]-DATE(YEAR([datecolumn]-WEEKDAY([datecolumn]-1)+4);1;3)+WEEKDAY(DATE(YEAR([datecolumn]-WEEKDAY(datecolumn-1)+4);1;3))+5)/7)

But in my case i had to get rid of the brackets [] and replace the semicolons ; with a comma ,

 

Why?

Beats me!