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[[File:Eratosthenes.jpg|right]]

[[File:Eratosthenes.jpg|right]]

'''Eratosthenes''' of Cyrene (275-194 B.C.) scientific writer, astronomer, geographer and poet, he was the first Greek [[mathematician]] to calculate the circumference of the earth and the tilting of the earth's axis during rotation. He used principles of [[Euclid|Euclidian]] [[geometry]].  

'''Eratosthenes''' of Cyrene (275-194 B.C.) scientific writer, astronomer, geographer and poet, he was the first Greek [[mathematician]] to calculate the circumference of the earth and the tilting of the earth's axis during rotation. He used principles of [[Euclid|Euclidean]] [[geometry]].  

He also invented the [[sieve of Eratosthenes]], which is a technique for separating composite from prime numbers in a natural series. The sieve appears in the ''Introduction to arithmetic'' by [[Nicomedes]].   

He also invented the [[sieve of Eratosthenes]], which is a technique for separating composite from prime numbers in a natural series. The sieve appears in the ''Introduction to arithmetic'' by [[Nicomedes]].