Unfortunately, the errors we make are not always evident or easy to track down. Often, the best way to discover the source of an error is to visually inspect the formulas and functions we have created.
The troubleshooting features of Excel are available in the "Formula Auditing" section of the "Formulas" tab.
Trace Precedents
Feature allows you to see which cells are referenced in a particular formula or function. Trace Dependents
Feature allows you to see which other cells reference a particular cell. Show Formulas
Feature displays the functions and formulas used in each cell of a worksheet instead of the formula or function results.