Wolfram Alpha is an answer engine developed by Wolfram Research. It is an online service that answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer as a search engine would.
Source: Wikipedia

I have been using Wolfram Alpha for graphing functions and calculus problems, but you can use it for any question that needs to be computed, such as calculations, weather tables, measurements and unit conversion etc.

Today I want to show you a way for embedding Wolfram Alpha’s results directly into Google’s search result page: the answer is a simple add-on for Firefox called Wolfram Alpha Google.

After you install it, just try to make a research on Google, and you will notice a box on the right side of your screen, containing Wolfram Alpha’s result to that particular query.

Plus, you will notice a small button on the upper right of the page: this will simply allow you to be redirected to the real Wolfram Alpha’s result page with a single click.

That’s basically what this plug-in does: so you can just download and install it at https://addons.mozilla.org/en-US/firefox/addon/12006

Bonus add-on: If you also want to add Wolfram Alpha to you default Firefox’s search engines without adding it manually, just go to this page and install the add-on that you will find. Now you will see that WA is integrated into your browser, enabling you to make researches quite faster.