WolframAlpha

Wolfram Alpha is an online search and answer tool, developed by Wolfram Research. This is an online tool that answers directly entered questions by calculating and giving the correct answer, not just providing a list of documents or web pages that may contain the answer like the way Google usually does. Wolfram can answer a lot of questions in all areas of Mathematics, Chemistry, Physics, Geography, History,...

Highlights:

• Has strengths in high-level math and science questions
  
• Intuitive interface, easy to use
• Diverse search topics from finance, stock trading to password generation, and more.
• Calculates easy to complex math problems, even providing detailed solutions if you need