Chalkboard is an unconventional, yet intuitive, "calculator." It allows you to describe equations the way you would with traditional paper and pencil. Only now, the number crunching is done for you, at the press of a button.
Chalkboard Lite is a simplified version of Chalkboard Calculator. The Lite version only contains operators for basic math.
Purchase the full version for over 34 more complex math operators, as well as support for imaginary/complex numbers, for-loops, string manipulation, trig, random, date and time access.
With the full version you may also send functions you created on your computer to your iPhone or iPod Toch.