I'd really like to emphasize the incredible value of the exact keyword phrase "math problems". Even if we were on page 1 for this keyword, but didn't show up for nearly any other phrase aside from our domain name, it would be fantastic.
Currently we're ranked #22, it looks like the highest we've been is #10. This phrase is definitely a niche, but not proprietary. Another close example is "PHP programming", which is even close in search volume according to Google Trends. In my example would it be worth switching from "www.RocketProgramming" to "www.Rocket-php-programming"? (included dashes because it was too verbose.. our scenario wouldn't be that bad.).