ES-Calc is a calculator and unit conversion program designed to be used by scientists and engineers. It allows evaluation of complex expressions and can handle most any function contained on a scientific calculator. An expression is entered in a form similar to a formula in a spreadsheet. A log of previously entered expressions can be recalled. User defined variables can be used to store and reuse previous results. It can solve a linear or nonlinear system of equations. ES-Calc has an excellent Units Conversion tool. A wide range of conversion factors is available. It also has a Hex/Octal/Binary Converter. Does clock arithmetic and also supports complex math (imaginary numbers) calculations. Help files include handy formulas such as integration tables, trigonometric formulas, geometric formulas (area, moment of inertia, etc.), and physical constants. Performs numerical integration, differentiation, root finding, etc. Can create plots of up to 6 user input functions (includes the ES-Plot program for plotting ASCII data files). Uninstall option easily removes everything from your computer. Has a small screen footprint. A great value.