Excel WEEKNUM function

Function              WEEKNUM

Description        Excel WEEKNUM function returns the week number of a specific date.

Syntax  WEEKNUM(serial_num, [return_type])

serial_number  The date for which you want to get the number of week.

return_type  [optional] A number that determines on which day the week begins. The default is 1.

Return_type	Week begins on
1 or omitted	Sunday
2	Monday
11	Monday
12	Tuesday
13	Wednesday
14	Thursday
15	Friday
16	Saturday
17	Sunday
21	Monday

Example: