2nd Millennium Invisible Calculator - Version 3.1 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. The calculator is able to count arithmetic expressions with brackets, trigonometrical functions, logarithms, exhibitors, roots etc.