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 694th installment in their series of digital spreadsheet magic tricks, you'll learn how the SUMIF function (and COUNTIF, etc.) cannot accept arrays. If you need to sum by year from transactional data the SUMIF and YEAR functions cannot be used together. Instead we can use the SUMPRODUCT function.