The Free Calculator has three windows or boxes: Edit Window, Result Window, and History Window. In the Edit Window you enter formulas using buttons and keyboard. When you use a keyboard, you can use all standard rules of text editing. The most convenient is use of numerical pad on the right of standard keyboard. Buttons also provides full functionality of Free Calculator. If you mistake in typing formula, like square root of a negative number, you just get a message in the Result Window that the formula is unclear. The Free Calculator tries to handle all possible ambiguities, following the standard mathematical rules. For example, formula 3/-4 - 5*2 will be treated as 3/(-4) - (5*2) . If you want to be completely sure in the result, use parentheses.A result number in the Result Window can be copied into Edit Window by clicking Result button. Sometimes it is useful during calculations. For example factorial button is absent, but you can easily calculate 10! by typing formula 1*2*3*4*5*6*7*8*9*10 or by series 2*3, =, Result, *4, =, Result, *5, =, Result, *6, =, Result, *7, =, Result,*8, =, Result, *9, =, Result, *10, =, imitating "old style calculators".
Calculation History Window has unlimited length. Use a scroll bar to navigate the window with log history. You can save the calculation history into text file or print it. Before this you can change size and style of the font in History Window.