The Man Who Knew Infinity

In 1913, a self-taught clerk from Madras named Srinivasa Ramanujan mailed pages of formulas to Cambridge professor G.H. Hardy. Hardy called it the most remarkable letter he had ever received.

Ramanujan saw math the way some people hear melodies: results arrived in his head almost fully formed. He filled notebooks that mathematicians still mine today. One of his formulas for 1/pi is so powerful that a single term already pins down roughly eight correct digits, with each extra term adding eight more.