The Calculator is much more than a simple four-function memory calculator. It can also act as a scientific calculator for students and scientists, a conversion calculator for metric and U.S. measures, and even a currency calculator for world travelers.
The little Calculator widget in the Dashboard is quicker to open, and it's great for quick four-function number crunches. But the standalone Calculator program is far more powerful. For example:
The calculator has three modes: Basic, Advanced, and Programmer (Figure 10-1). Switch among them by choosing from the View menu (or pressing ⌘-1 for Basic, ⌘-2 for Advanced, or ⌘-3 for Programmer).
You can also cycle among the three modes by repeatedly clicking what, on most windows, is the Zoom button (the green round dot at upper left). It's a first for the Mac—a Zoom button that changes function each time you click it—but it's kind of neat.
You can operate the calculator by clicking the onscreen buttons, but it's much easier to press the corresponding number and symbol keys on your keyboard.
you go, you can make Calculator speak each key you press. The Mac's voice ensures that you don't mistype as you keep your eyes on the receipts in front of you, typing by touch.
Just choose Speech → Speak Button Pressed to turn this feature on or off. (You choosewhich voice does the talking in the Speech panel of System Preferences.)
If you have a laptop, don't miss the embedded numeric keypad, superimposed on the right side of the keyboard ...