Road Sign Math is a site which offers a slightly “brainier” alternative to the classic Slug Bug driving game. The game has a comprehensive list of rules, but the basic premise is: people take photos of roadsigns that contain numbers which, when solved, will formulate an equation.

An example follows:

9+6=15

So next time you’re going on a road trip make sure and take the digital camera along and see if you can’t find some road sign math of your own to upload to the site.