What is Eratosthenes?

He was an ancient Greek mathematician of the 2nd/3rd century BC, as well as a poet, geographer, musical composer, scholar, and astronomer. He was the first Greek to estimate the circumference and tilt of the earth. He created a map of the earth based on the knowledge available at the time. He was highly respected, and his calculations of the earth's circumference were used for hundreds of years. Today, his method for finding prime numbers from 1-100 is known as the 'Sieve of Eratosthenes' and is taught in math textbooks.