By: Mahfuza Anika Era

In reply to Jamz.

Hi JAMZ,
Thank you for your comment. There is an error in the second portion of your formula. As your week starts on Monday, you must apply the WEEKNUM function’s return type as 2. Here is the corrected formula:
=WEEKNUM(B1,2)-WEEKNUM(DATE(YEAR(B1),MONTH(B1),1),2)+1

Regards
Mahfuza Anika Era
Exceldemy