Microsoft® Excel® 2010 Formulas & Functions Inside Out

WEEKNUM()

Note

In Excel 2003, this function is available as an add-in.

Syntax. WEEKNUM(serial_number,return_type)

Definition. This function returns an integer for the week number for the given date.

Arguments

• serial_number (required). The date for which the week number is calculated.

• return_type (optional). A number indicating on what day the week begins. This argument has the different options depending on the version of Excel you are using. In Excel 2003 and earlier, there are two return types:

  • 1. System 1 (the default setting): The week begins on Sunday. The weekdays have the numbers 1 through 7, starting on Sunday.

  • 2. System 2: The week begins on Monday. The weekdays have the numbers 1 through 7, starting on Monday.

  In Excel 2010, the System 1 return ...