There are many symbols that can't be typed on a standard keyboard, but what you might not know is that thousands of symbols can be typed with just the Alt key and the Number Pad.

Next time you need to insert uncommon symbols (e.g. copyright, trademark, or square root), try this. Make sure Num Lock is turned on, hold down the Alt key, type one of the following number combinations, then let go of Alt. For international keyboards, you must use the Left Alt key.