Acqualia Software OU has Soulver 2 in the Mac App Store for FREE (regularly $8.99) for a limited time.
Soulver helps you do quick calculations and work things out. Use Soulver to play around with numbers, do “back of the envelope” calculations, and solve day-to-day problems.
Annotate your numbers with words, so that they make sense to you. Soulver picks out the numbers and calculates your answer as you type. Do calculations over multiple lines, and refer to previous lines, much like a spreadsheet.
Soulver is great for adding things up, doing all kinds of percentages easily, and converting things, like currencies. It’s quicker to use than a spreadsheet, and smarter and clearer than a traditional calculator.