CONNX has four functions to determine which week a date occurs in:

• WEEK(timestamp) for ISO week

• WEEKE1(timestamp) for Excel WEEKNUM(CELL,1)

• WEEKE2(timestamp) for Excel WEEKNUM(CELL,2)

• WEEKS(timestamp) for simple week numbers.

Depending on how you want to calculate which week a date occurs in, one of these functions should satisfy your needs.

 

Microsoft has an excellent article explaining the differences between the four functions.

 

Here is an example of how the four functions calculate specific week numbers: