One of my favorite tools on the web is Wolfram Alpha because it speeds up the double checking of my work in my classroom. There are so many ways to use it such as asking it to solve, simplify or graph functions. It gives a very accurate answer and with the Pro account it gives the step by step solutions. I have found two other ways to access Wolfram Alpha other than just going to their sites and it speeds up the checking of my work.
1) Set up a Shortcut in the Omnibox.
I have setup my own search short cut in the Omnibox of Chrome so that all I have to do to search Wolfram Alpha is type "w" and the press the space bar. After that I can input anything thing and Wolfram Alpha will do its best to answer.
2) Ask Siri.
If you open Siri on your iPhone and ask it to "Solve two x plus one equals five" it will search Wolfram Alpha's database and provide the answer. This works well with graphing and simplifying functions too.