New to Microsoft Excel? Looking for a tip? How about a tip so mind-blowingly useful as to qualify as a magic trick? You're in luck. In this MS Excel tutorial from ExcelIsFun, the 204th installment in their series of digital spreadsheet magic tricks, you'll learn how to use the SUMPRODUCT and EXACT functions in an array formula to add the sales for a sales representative where lower and upper letters matter (i.e., are case sensitive) in the criteria (conditions).