Wolfram|Alpha

Wolfram|Alpha answers questions with computed results, not a list of links. It is a computational knowledge engine that takes plain English input and returns expert-level answers across a wide range of subjects, including math and research data.

You type a question the way you would say it, and the engine works out the answer.

The free version covers the basics, but it has limits.

Step-by-step solutions, which matter most if you are using Wolfram|Alpha to learn math, sit behind Pro.

So do uploads of data, images and files for analysis, interactive visualizations, and the web apps for exploring particular interests.

The site requires JavaScript to run.

Simple queries can come back with more output than you wanted, which some people find overwhelming.

Pro is the version to look at if you want to see how an answer was reached, not just the result.