The Excel ISOWEEKNUM function (new in Excel 2013) returns the week number of a date serial number. The first Monday of the year marks the start of week 1.
Tip: It also works with dates input as Text, but this could be unreliable so it's always best to work with date serial numbers.
Excel ISOWEEKNUM Function Syntax
Where the date represents a date in a format Excel recognises known as the date-time serial number. It can be contained in a cell, as shown in the examples below, or entered directly into the formula. E.g
Excel ISOWEEKNUM Function Examples
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|Excel WEEKNUM Function||Returns an integer representing the week number (from 1 to 54) of the year from a date serial number|
|Excel MONTH Function||Returns the month from a date serial number.|
|Excel DAY Function||Returns the day (of the month) from a date serial number|
|Excel YEAR Function||Returns the year from a date serial number|
|Excel End of Period Dates||Calculate fiscal period end dates|