How to Add the difference between 2 number columns in Excel

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 339th installment in their series of digital spreadsheet magic tricks, you'll learn how to use the SUMPRODUCT function to add the difference between two columns of numbers based on two criteria.