I haven't succeed with a research of the phrase below cited from the House M.D. - Love Hurts, episode 7x06.

Dr. Lisa Cuddy:

> 
> The two of you have a combined IQ north of 300.
> 
> 
> 

What does **north of xxx** means in case of using with a number, not direction?

Where is likely the usage of this phrase and in what situations? 

Do exist another phrases using others of he world sides (sout, west, east) in a similar context?