How can we use math to communicate with aliens?

[Brad12d3]

I am curious to hear some theories on how we might communicate with an alien race with math. Let's say that there is a one way line of communication between the two of us. We don't have the luxury of showing each other writings back and forth trying to figure out how to communicate. They know nothing of our written mathematical symbols, or even Earth coordinates. However, they want to lead us to a meeting spot somewhere on our Earth and they need to be able to communicate where this location is.

I know it's kind of a crazy idea, but I was just curious what ideas people might come up with.

 

[LCKurtz]

They land a flying saucer on the White House lawn, open the hatch, and wait.