At first glance, the table below looks like an ordinary table created in Pages (part of Apple's iWork suite).

In fact, it is just a basic table. That is, until we add a formula to do some calculations. In this case, we want to total each of the columns represented by a city name. We could simply calculate the total in our head, and enter the resulting number, but when either of the variables change, our total is then incorrect. A better way is to use a simple summation formula.

The key to beginning to add a formula is the "=" key. Once you are in the cell that you want to enter the formula, hit the "=" key, and things will change. First of all, reference tabs appear on the top and side of the table, helping you to identify the column and row identifier (i.e.: A, B, C, 1, 2, 3, etc). The other thing that appears is a formula bar. This is where you will want to enter your formula.

In order to total the "New York" column, our formula would be =SUM(A2:A3), as shown below:

Obviously, the above example is very simplified, but as your tables becomes complex with lots of variables, you can see how valuable these formulas can be. For a larger sampling of formulas available, click on the button to the left of the formula bar labeled "fx". SUM, COUNT and MIN are just some of the available calculations.

One thing to note is that the formula feature in iWork isn't nearly as powerful as what you will find in Microsoft Excel, but then again, it's designed for simplified calculations (enough to satisfy your need for publications and presentations). For the more complex calculations, head over to Microsoft Excel, which is an amazing spreadsheet application.