2nd Millennium Invisible Calculator allows you to make calculations in any place where it is possible to enter expressions (e.g. text editor, lines of input, etc.). After starting the calculator, it is automatically placed in your system tray. All you have to do to count an expression in any text editor is to type it, select it, and press the hotkey (by default it is Ctrl + F11). The result will be substituted in the document.

Lucky - A compact and powerful calculator that supports skins. It also supports four notations: decimal, hexadecimal, octal, and binary. It contains 50 built-in functions. Calculates an expression without pressing any additional buttons or keys. The history contain list of calculated expressions. Automatic clipboard copy. The icon is minimized in the system tray and can be called up by a hotkey.