Excel function WEEKNUM and change week start day.

I have been using week number function from quite some time now, but I came across a situation where I need to change week start from Sunday to Thursday.

Syntax for WEEKNUM

WEEKNUM(serial_number,[return_type])

Till now I had never used return type argument as it was optional but this does the trick. By default if not provided its 1 i.e. Sunday. But it has other options as well

Return_Type Start Day of Week
1 Sunday
2 Monday
11 Monday
12 Tuesday
13 Wednesday
14 Thursday
15 Friday
16 Saturday

I used

How to use Date Function in Excel 2010

How to use Date Function in Excel 2010

=WEEKNUM(A1,14) and got my result.