Eratosthenes
Born	276 BC Cyrene
Died	194 BC (Around 82) Alexandria
Occupation	Scholar Librarian Poet Inventor
Known for	Sieve of Eratosthenes Foundation of Geography

Eratosthenes of Cyrene (276 – 194 BC) was a 3rd century BC Greek mathematician, geographer and astronomer. He was head of the Library of Alexandria from 240 BC until his death: this was the most important library of the ancient world.

According to the Suda, his contemporaries nicknamed him Beta, (the second letter of the Greek alphabet), because he was the second best in the world in almost any field. Eratosthenes was a friend of Archimedes, who also lived and worked in Alexandria. Archimedes was the greatest mathematician and inventor of the age, so perhaps the Beta nickname was not unjust.