Countdown

Abraham de Moivre was recognized by his peers as a talented mathematician and evidently respected by gamblers too for his work in probability theory. One of his most notable mathematical achievements was de Moivre's identity, which can be derived from Euler's formula (which, by the way, blows my mind the more I learn about it).

Apparently he counted down to his own death. He noted that he was sleeping 15 minutes longer each day, and thusly calculated accurately the day of his death based on this. Sounds like one of the stranger episodes of The Twilight Zone.