When you create a formula, you generate a single result based on the operators, functions, and data that you used. This situation makes sense when you're nailing down last year's profit-loss report, but it's not always as handy when you're making projections for the future. In these cases, it's often helpful to compare several possibilities. One tool you can use is a variable data table.

A variable data table is simply a table that shows multiple results, based on different source data. You could use a variable data table to see how the return of an investment varies based on different interest rates. Because Excel shows all the results side by side, you can quickly compare them.