Soulver has some basic trig functions, currency and unit conversion, and logical operators, and you can save your calculations to iCloud or Dropbox or send them as HTML-formatted emails. If you have $87 to spend at a sale and prices are 45 percent off, you can easily figure out your buying power by long-pressing the % key to reveal the “% off what is” option. Soulver makes it easy to do some math problems that aren’t always intuitive, thanks to a long-press overflow menu on many of the buttons. Answers are always updated instantly, without needing to press the enter key-it simply exists to end a line so you can use the result in your next calculation. If the first part of your long list of calculations has a 4 you want to change to a 4.025, you can just tap the number way up at the top of your list, change it, and see the whole math chain update in response. Then, you can make a change anywhere and see the results update throughout your whole chain of operations. You can use the results of one line to flow in the next line, and see a clear visual representation of that. The basic conceit of Soulver is this: the calculator sits in the bottom third of the screen, with a running log of your operations and results up above. Soulver’s unique presentation makes it easy to perform and edit a string of related calculations.