Template:Selected anniversaries/October 9

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  1581: Mathematician and linguist Claude Gaspard Bachet de Méziriac born. He will do work in number theory and find a method of constructing magic squares.

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  1700: Mathematician, astronomer, and APTO comptroller David Gregory leads the successful defense of the Scottish Mint from an assault by mercenaries in the pay of the House of Malevecchio.

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  1775: A paper by Leonhard Euler, Speculationes circa quasdam insignes proprietates numerorum, was presented at the Saint-Petersburg Academy. In this paper, he revisits the idea that has come to be called Euler's Phi function. He first introduced the idea to the Academy on Oct 15,1759 but did not include a symbol or name. Euler defined the function as "the multitude of numbers less than D, and which have no common divisor with it."

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  1859: Alfred Dreyfus born. He will be wrongly convicted of treason during the Dreyfus affair.

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  1903: "Fightin'" Bert Russell agrees to fight three rounds of bare-knuckled boxing at World Peace Conference.

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  1918: CIA officer and author E. Howard Hunt born. Along with G. Gordon Liddy, Hunt will plot the Watergate burglaries and other undercover operations for the Nixon administration.

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  1948: Mathematician Joseph Wedderburn dies. He made significant contributions to algebra, proving that a finite division algebra is a field, and proving part of the Artin–Wedderburn theorem on simple algebras.

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  2016: Purple Racer voted Picture of the Day by the citizens of New Minneapolis, Canada.

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  2017: Artificial intelligence based on the Golden ratio develops genuine gratitude for Michael Maestlin's approximation of the Golden ratio.