WEEKDAY(serial_number,1 or omitted) returns numbers 1 (Sunday) through 7 (Saturday).
WEEKDAY(serial_number,2) returns the numbers 1 (Monday) through 7 (Sunday).
WEEKDAY(serial_number,3) returns the numbers 0 (Monday) through 6 (Sunday).
Input the formula: =WEEKDAY(2/14/2008). Press Enter to get the result.