Mrs. Ballarini

1 + 1/2 + 1/3 + 1/4 + ... grows forever, but slowly. To pass 100 you need about 1.5 × 10⁴³ terms. If you’d added one term every second since the Big Bang, you’d be at about 41.

Every four-digit numerical palindrome (e.g. 1991) is a multiple of 11 abba = 1000a + 100b + 10b + a = 1001a + 110b = 11(91a + 10b)

On this day in 1623 Blaise Pascal was born. At nineteen he built a machine of brass gears that could add and subtract by turning dials. It was one of the first mechanical calculators ever made. He went on to invent the theory of probability in a series of letters with a lawyer named Pierre de Fermat, working out how to fairly divide the stakes of a game of chance that had been stopped partway through. He proved that air has weight, left behind a book of devastating aphorisms, and died at thirty-nine. The unit of pressure is named for him and so is a programming language.

On this day 150 years ago William Sealy Gosset was born. He spent his whole career as a brewer at Guinness, working on a problem the textbooks ignored: how to draw conclusions from tiny samples, like four plots of barley or a handful of hops. The statistics of the day assumed large samples so Gosset invented the statistics of small ones. Guinness barred its employees from publishing after one of them leaked trade secrets, and did not want competitors knowing it used science to brew beer so when Gosset published his method in 1908 he signed it with a pseudonym: Student. Every clinical trial, lab experiment and A/B test that runs a t-test today is using the work of Student. The most famous name in statistics is a fake one.