All spreadsheets support lookup functions, tools that return a value from a table by looking up another value in the table. An income tax table is a good example. You can write a formula that uses Vlookup() to determine the tax rate for a given income amount.

The lookup functions in Excel and 1-2-3 are only appropriate for one-way lookups, however. If you need to perform a two-way lookup, you'll need more than the standard functions. FIGURE 2 shows a simple example

The formula uses the Index() function, with three arguments. The first is the entire table range (A1:A14). The second uses Match() to return the offset of the desired month in column A. The third argument uses Match() to return the offset of the desired product in row 1.

Excel users can also take advantage of natural-language formulas. For example, enter =June Sprockets to return Sprocket sales for June. If natural-language formulas aren't working, select Tools*Options, click the Calculation tab, and place a check mark next to Accept labels in formulas.

-- John Walkenbach