Blaise Pascal, who built an early mechanical calculator, was born

On June 19, 1623, Blaise Pascal was born in Clermont (now Clermont-Ferrand), in the Auvergne region of France. Schooled at home by his father, he was a prodigy: at sixteen he wrote a treatise on conic sections, and his name still attaches to a theorem in projective geometry.

In the 1640s, watching his father grind through tax accounts, Pascal built a geared mechanical adding machine later called the Pascaline. Only around fifty prototypes were made, and it never sold widely, but it placed him among the first inventors of the mechanical calculator.

A teenager’s boredom with his father’s ledgers helped seed the history of computing.

His most consequential mathematics came later. In a 1654 correspondence with Pierre de Fermat over a gambling puzzle, Pascal helped lay the foundations of probability theory — work whose importance was not fully recognized until Jacob Bernoulli built on it decades afterward. He died in Paris in 1662, aged just 39.