### Mathematical moments - Taking chances with De Moivre

Abraham De Moivre

Born on the 26th of May 1667 in Vitry-le-Francois, France

Died on the 27th of November 1754 in London, England

When De Moivre first came across Newton's famous work the "Principia" he was so struck by its depth and rigour that he immediately bought a copy and cut it into pieces - carrying just a few pages at a time was the only way he could study the work while making his rounds tutoring private students in London.

But it wasn't just dedication that gained him full marks. Since an early age he had been interested in maths, especially in games of chance, and he is today known as a pioneer of probability theory and of analytic geometry. His "Doctrines of chance" presented the broadest and most rigorous treatment of probability of its day, and he is credited with deriving the normal curve and developing the concept of standard deviation. His name is famously attached to a formula that gives geometric meaning to powers of complex numbers by expressing them in terms of trigonometry.

De Moivre's eminence as a mathematician was recognised by many of his most prominent contemporaries, including Newton, who he was friends with, and Leibniz. Interestingly, the Royal Society called upon him to referee Newton and Leibniz's dispute about who had first invented the calculus.

Sadly, though, De Moivre's genius was never rewarded professionally. As a French national who had been expelled from France (after a prison sentence) because of his protestant religion, he remained a foreigner in London. Despite the support of his prominent friends he was never employed by a university. He made a living as a private tutor and died in poverty.

Death played an important role in his mathematics. Together with Halley, who gave his name to the comet, he set about investigating mortality statistics, laying the foundations for actuary theory used by life insurances.

Most curiously, De Moivre is said to have used maths to predict his own death. He had noticed that he was sleeping 15 minutes longer every day. Analysing the arithmetic progression 15, 30, 45, .... , he calculated that on the 27th of November 1754 he would sleep through the full 24 hours. He was right - it was the day he died.

Find out more about De Moivre on the MacTutor history of maths archive, about De Moivre, death and statistics in this past Plus article, and about complex numbers and trigonometry on cut-the-knot.

*posted by Plus @ 4:21 PM*