Wolfram Alpha: Calculating for you!

This site, Wolfram Alpha, gives you the power to not just ask a question and receive webpages, but to ask a question and receive the calculated response.

As in, it literally could do your math homework for you!  Or show you the steps if you get stuck.  :)  But it does any calculation, not just math.

Here are some videos to explain better:






How can you use this?