An anonymous reader writes "One of the basic utilities supplied with any operating system is a desktop calculator. These are often simple utilities that are perfectly adequate for basic use. They typically include trigonometric functions, logarithms, factorials, parentheses and a memory function. However, the calculators featured in this article are significantly more sophisticated with the ability to process difficult mathematical functions, to plot graphs in 2D and 3D, and much more. Occasionally, the calculator tool provided with an operating system did not engender any confidence. The classic example being the calculator shipped with Windows 3.1 which could not even reliably subtract two numbers. Rest assured, the calculators listed below are of precision quality."