DayOfWeek
Purpose 
Returns a number representing the day of the week that date falls on.
Format 
DayOfWeek(date)
Parameters 
date - any calendar date
Data type returned 
number
Originated in 
FileMaker Pro 6.0 or earlier
Description 
The number 1 represents Sunday, 2 represents Monday, 3 represents Tuesday, and so on. For example, you can find out on what day of the week a holiday occurs.
Important  To avoid errors when using dates, always use four-digit years. For more information about how FileMaker Pro handles two-digit dates, see Conversion of dates with two-digit years.
Examples 
DayOfWeek(“10/8/2014”) returns 4.
DayOfWeek(Date(10;9;2014)) returns 5.
DayOfWeek(ProjectDue) returns 3 when the date in ProjectDue is 10/7/2014.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas