This article is an excerpt from John Walkenbach's Favorite Excel 2007 Tips & Tricks by John Walkenbach. A.k.a. Mr. Spreadsheet, John is arguably the foremost authority on Excel. His forty-plus books include Excel 2007 Power Programming with VBA, Excel 2007 Formulas, and the bestselling Excel 2007 Bible, all published by Wiley. He has also written hundreds of articles and created the award-winning Power Utility Pack. Visit Wiley.com to learn more about this book.

Formulas can work with cells in other worksheets, which is useful when you want to calculate the sum of values that are entered in different worksheets.