You know about the Mac’s Calculator app. (You don’t? Look in the Applications folder.) But, did you know that the Calculator can do all sorts of fancy stuff, like sines and cosines and exponents and factorials and random numbers and square roots? Just click the green button (the one you’d click to zoom in other apps, 3rd from the left for my color-blind friends) and you get the advanced calculator. Click it again and it’s back to normal.