Use Week Numbers in Google Sheets with WEEKNUM

If you work in an environment that uses numbered weeks, you might find Google Sheets’ WEEKNUM function useful. Here’s the syntax:

WEEKNUM(date, [type])

date is the date for which you want to find out the week number. This parameter must be a reference to a cell containing a date, a function returning a date type, or a number.
The parameter type is optional (the default is 1) and is a number representing the day on which a week starts. Entering 1 (or omitting the parameter) will start each week on a Sunday, while entering 2 will assume Monday as the first day of each week.

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