I am a math geek, so most of my browsing is mathematically oriented. I've noticed that for sites that use HTML math symbols Firefox, in some instances, does not render the symbol but instead gives me a little rectangle with four single digit numbers contained within. An example can be found here. This is an example of a problem for which I have no idea what to google for, hence the screenshot. I do not know if this occurs in any other Firefox but 0.9.1. Also, I am using the binary available from the Firefox site.

My question, does anyone know of the necessary font package for Firefox to display the symbols?