You’d be forgiven for thinking that the biggest differences between calculator programs for Mac OS X are found in the functions they offer and the way their buttons are laid out. Soulver, on the other hand, aims to change the way you make the calculations themselves. Although you can type traditional mathematical equations, such as 365 x 24 x 60, into Soulver’s list-like interface, the program is unique in letting you also use something approaching normal language.

For example, if you’re trying to figure out the price of a $199 product at a 15% discount, you can just type 15% off $199. To convert currency, you can type $50 in Yen. To convert time, type 5 minutes 18 seconds in seconds. A handy Total display shows the sum of all the current window’s answers.

If you’re a spreadsheet pro, Soulver can also reference results by line: 18% of line7 calculates 18% of the result from line 7. You can even drag answers from the answer column to another calculation line, and you can edit existing lines to get updated calculations. Creating temporary variables, which can be used in subsequent calculations, is as simple as typing x=73.

Finally, you can include labels, section names, comments, and text within your calculations, which is useful when saving a Soulver window, or exporting it to another format, for later reference.

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[Dan Frakes is a Macworld senior editor.]