Paul Erdos (sometimes Erdős or Erdös) is a Hungarian mathematician who gained fame from his prolific essays and papers concerning numbers. For a person who only loved numbers, scientists coined the term "Erdos number" to pertain to a "collaborative distance" comparing a person to Erdos himself in authoring mathematical papers. The web comic XKCD used the "Paul Erdos" term to pertain to a student who took so long to finishing the recent Math Regents exams.
No wonder, search engines was spiced up with searches "who is paul erdos" because of this joke. It seems most people do not know who Paul Erdos was. Here's Paul Erdos Wikipedia page for you and here's the XKCD web Comics which used the Paul Erdos joke to spice up the search engines.
