How to Use Mountain Lion's Calculator
Need to do some quick math? The Calculator application in OS X Mountain Lion gives you a simple calculator with all the basic number-crunching functions that your pocket calculator has. To use it, you can either click the keys with the mouse or type numbers and operators (math symbols such as +, –, and =) using the number keys on your keyboard (or numeric keypad, if you have one).
Calculator also offers a paper tape (Window→Show Paper Tape) to track your computations — and, if you want, provide a printed record. It can even speak numbers aloud (Speech→Speak Button Pressed and Speech→Speak).
The most useful feature in the Calculator (after the paper tape) is the Convert menu — more specifically, the currency-conversion feature. It actually checks the Internet for the exchange rate before calculating the conversion for you. That’s very cool.
Beyond that, Calculator has three modes: Basic, Scientific, and Programmer. Basic is the default, and you access the other two modes as follows:
Pressing Command+2 (View→Scientific) turns the formerly anemic calculator into a powerful scientific calculator.
Choosing View→Programmer (Command+3) turns it into the programmer’s friend, letting you display your data in binary, octal, hexadecimal, ASCII, and Unicode. It also performs programming operations such as shifts and byte swaps. (If you’re a programmer, you know what all that means; if you aren’t, it really doesn’t matter.)