Leonhard Euler was born in Basel, Switzerland on April 15, 1707. It could be said that he came from humble beginnings; his father was a pastor. As a boy, his father hired mathematicians to tutor him privately, and when his father sent him away to study in a theological facility, Euler was more interested in studying mathematics and spent much of his time on it. In college, one of his professors was the renowned Bernoulli, famous for the Bernoulli principle. Euler spent a large amount of his time in St. Petersburg and Berlin. He joined the St. Petersburg Academy of Sciences in 1727, but Frederick the great called him back to Berlin in 1741. He was married twice and had a total of 13 children.
Over his lifetime, Euler published 886 books and papers. He is well known for the number "e", and his theorem on angles, which states that every rotation has an axis. E, an irrational number, is one of the most important numbers used in mathematics today. Many of Euler's works were also related to his teacher, Bernoulli, and his formulae and theorem. Bernoulli used the number e to calculate compound interest problems. However, Euler's works were not entirely devoted to mathematics. He often immersed himself in philosophical debates, and studied those held by prominent philosophers such as Descartes, Newton, and Galileo.
While Euler had thirteen children, only five survived past infancy. Some sources remarked that his ability to concentrate was impeccable, saying he would often work formulae with children running around him and playing. He was said to have been able to recite large passages word for word, and once solved a quarrel between tow students by calculating a difference in their answers at the 50 th decimal place in his head. At a later age, he began to lose his sight. In one of his eyes, he began to lose it because of an accident during an experiment; in the other, he had a disease and a surgery in attempt to fix it had only made his vision...