You may be one of the many people who use RegEx as a way to create the variations for answers in math questions in their online courses. I've heard it's simple to learn and use, but I don't do math so I don't use RegEx. However, my Resources website does have a page of reference and resource sites on the topic.
Here's one of them: RegEx Side. Says the site's author: "Regular Expressions are a necessary evil. So necessary they are, that they could be considered good." See his recent posting, Regex Cheat Sheet.