Multiple choice technology web technology Converts a serial number to a day of the week COUNTWEEK WEEKNUM WEEKDAY COUNTDAY Reveal answer Fill a bubble to check yourself C Correct answer Explanation WEEKDAY returns a number (1-7) representing the day of the week for a given date serial number. By default, Sunday=1 and Saturday=7, though this can be customized. COUNTWEEK and COUNTDAY are not valid Excel functions.