New to Excel? Looking for a tip? How about a tip so mind-blowingly advanced as to qualify as a magic trick? You're in luck. In this Excel tutorial from ExcelIsFun, the 533rd installment in their series of digital spreadsheet magic tricks, you'll learn how to create a formula to calculate the difference between start date/time & end date/time excluding holidays and weekends. This is accomplished with recourse to Excel's NETWORKINGDAYS and MOD functions.