So, unless you were planning on paying him a visit, you probably didn't pay attention to the number on Neo's door when you first watched the movie. So you'll just have to trust us when we say he lives in Room 101.

Okay, so what? It's just a number, right? Well, yeah, it is, but it's also a lot of other things. 

• Neo is The One, so it's no surprise he that the place he lives in has two ones in it.

• Also, 101 is a number used for a lot of introductory courses at the university level and has since taken on the meaning of a "general introduction" or "place to start." In this case, 101 is the beginning of Neo's journey of being The One.

• Another possible interpretation of room 101 is an allusion to Orwell's 1984, where Room 101 is the ultimate torture chamber which contains everyone's worst nightmare (rats for Winston, naturally). This is interesting although whether Neo's cluttered living space is his worst nightmare is iffy. Even considering the Matrix as a whole, its purpose isn't to torture people; it's to placate them.

• And one more: 101 is also binary code, which gives some hints to the world's actual makeup.

But there's another room number that appears a few times: room 303. It's the room that Trinity is in during the opening scene and it's the room that Tank directs Neo to as he flees from the agents. So it's a convenient entrance and exit from the Matrix, but it's also symbolically important. Trinity—see our Tools of Characterization for more on her name—is all about the tres. The number 303 not only contains 3s but also has three numbers.