LP-Calc

LP-Calc is a fully functional scientific calculator program that can be used as an alternative to the Microsoft Calculator program that comes with Microsoft Windows.

As well as doing basic calculations, LP-Calc can also be used to assist with programming as it understands functions (and some statements) from VBScript and JavaScript.
If you are familiar with Visual Basic programming it is suggested that you use the VBScript functions, as most are identical to Visual Basic functions.