Note: the WEEKDAY function will return a value even when the date is empty.
Take care to trap this result if blank dates are possible.
WEEKDAY Function
The Excel WEEKDAY function takes a date and returns a number between 1-7 representing the day of week. By default, WEEKDAY returns 1 for Sunday and 7 for Saturday, but this is configurable. You can use the WEEKDAY function inside other formulas to check the day of week.
