I admit it. Even as a life long (casual) soccer fan I never really knew what exactly soccer jersey numbers meant.
I got the general area on the field where numbers played. I knew good players got 9 and 10. Didn't really ever put it all together though.
Here's the general rundown of soccer numbers and their corresponding positions.
No. 1 - Goalie
No. 2 - Right Back
No. 3 - Left Back
No. 4 - Center Back
No. 5 - Center Back
No. 6 - Defensive Mid; Center Back
No. 7 - Right Mid
No. 8 - Attacking Mid; Box-to-Box
No. 9 - Target Forward
No. 10 - Playmaker; Forward
No. 11 - Left Mid; Wing
As you can see, past 11 is never really accounted for. Ya know, because you play 11 men.
MLS has a pretty good run down of how formations effected numbers and their meaning. Worth a watch.