How to Add across sheets in Excel with 3D cell references

Whether you're interested in learning Microsoft Excel from the bottom up or just looking to pick up a few tips and tricks, you're in the right place. In this tutorial from everyone's favorite digital spreadsheet guru, ExcelIsFun, the 8th installment in his "Highline Excel Class" series of free video Excel lessons, you'll learn how to add across sheets using 3-D cell References and the SUM function.