In many Excel worksheets, formulas are used in a very straightforward way. The actual formulas and the cells they reference can be seen. Finding errors is easy because you're working with a limited number of cells. In more complex calculations, however, a formula in one cell may depend upon the results of a formula in another cell. There are no limits on the number of references a formula can support, so a formula can reference cells that use any number of other cells, which may contain additional references! To help you spot troubles with more complicated formulas, Microsoft offers some built-in utilities and features that provide assistance in tracing formulas in Excel 2007.