Passage: To be assigned an Erdős number, someone must be a co-author of a research paper with another person who has a finite Erdős number. Paul Erdős has an Erdős number of zero. Anyone else's Erdős number is k + 1 where k is the lowest Erdős number of any co-author. The American Mathematical Society provides a free online tool to determine the Erdős number of every mathematical author listed in the Mathematical Reviews catalogue.Erdős wrote around 1,500 mathematical articles in his lifetime, mostly co-written. He had 511 direct collaborators; these are the people with Erdős number 1. Watu ambao wameshirikiana nao (lakini sio na Erdős mwenyewe) wana idadi ya Erdős isiyo na kikomo (11,009 kama ya watu wa 2015), wale watu ambao wameshirikiana na mtu ambaye ana idadi ya Erdős ya 2 (lakini sio na Erdős) au k ni idadi ya chini ya Erdős ya mwandishi yeyote.
Erdős idadi ya infinity