Today’s Google Doodle celebrates the 306th birthday of Swiss mathematician Leonhard Euler (1707-1783), who made important contributions to the study of geometry, algebra, calculus, mechanics and number theory.

Born Apr. 15, 17o7, in Basel, Switzerland, he was the son of a Calvinist minister who started college at the University of Basel at 13 and earned his master’s degree in philosophy by age 16. While Frederick the Great invited him to join the Berlin Academy at one point, he spent most of his career working in St. Petersburg, Russia.

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Euler was one of the most published mathematicians of all time, penning more than 800 papers (many in Latin) before his death at age 76. In fact, he produced nearly half of his work after going completely blind at age 59. Most notably, he wrote about the significance of “e,” an irrational number and the base of natural logarithms that is approximately equal to 2.7183. Readers of the journal *Mathematical Intelligencer *voted his equation “e^{i(pi)} + 1 = 0″ the “single most beautiful equation in all of mathematics” in a 1988 poll*.*

Euler may also be the father of sudoku, for he created the Latin Square, “arrangements of groups of numbers in grids that do not repeat vertically or horizontally,” according to a 2005 Los Angeles *Times* article.

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He was also known for having an amazing memory and reportedly could recite every word of Virgil’s *Aeneid*.* *

Euler worked furiously up to the end of his life; on the day he died of a cerebral hemorrhage on Sep. 18, 1783, he had been calculating how high hot-air balloons can rise, as well as the orbit of the planet Uranus, which had recently been discovered.

“Euler’s work is at the root of almost every equation, formula, theorem or other relationship used in mathematics, from the simplest to the highest levels,” Afred S. Posamentier, former dean of the School of Education at the City University of New York, wrote in a *Newsday *editorial published* *on the occasion of Euler’s 300th birthday in 2007. Ronald S. Calinger, mathematics historian at the Catholic University of America, argued in the Washington *Post* that Euler is one of “the four greatest mathematical scientists of all time,” alongside Archimedes, Isaac Newton, and Carl Friedrich Gauss.

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