Created attachment 117829 [details] spreadsheet I cannot quite understand how the function WEEKNUM is meant to work as the documentation and the attached indicate that the result should be different. See online documentation at https://help.libreoffice.org/Calc/WEEKNUM. I am using Version: 4.4.3.2.
Changing the product to LibreOffice, this is not related to LibreOffice Online.
Created attachment 118767 [details] correct formula Hello, see an attachment. First parameter needs to be a date.