Calculator for Windows is a program for numerical calculations. Unlike usual calculators or the Windows built in calculator, this program receives your inputs in a text editor. This is very useful for longer formulas. So you can see your whole input all the time, and if necessarily a correction in the formula is very simple. A further advance is, that important constants are defined and can be used easily. In addition to this pre-defined mathematical and physical constants it is possible to define user-constans.