How to Create nested unique lists in Excel via array formulas

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 251st installment in their series of digital spreadsheet magic tricks, you'll learn how to create a unique list of customers within a unique list of sales reps using a series of standard formulas in tandem with a few array formulas.