A friend asked me for help with a Chemistry equation involving the composition of a penny. Using some patience, I figured out what I think was the right equation. I wrote it out in a text editor, then opened up Calculator and then tried pasting it in. It worked like a charm:
(8.95 * 97.3) + (7.14 * 2.7)
I had no idea you could do this; pretty awesome.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050127015044384