It can get you a job? In Mr Magorium’s Wonder Emporium, the first question the prospective accountant was asked was Name the Fibonacci series from its eleventh to its sixteenth. The accountant answered correctly and after another couple of questions he was hired.
Well that’s a movie. A real life application came from Turan, which I will quote from the book “My Brain is Open” by Bruce Schechter.
In 1935 Turan wrote a paper on a problem in number theory with Erdos, which appeared in the Russian Bulletin of the Institure of Mathematics and Mechanics of Tomsk. Ten years later, in postwar Budapest, Turan was stopped by a Soviet patrol … The soldier demanded that Turan produce his papers*. Turan had lost his ID a few days earlier evading another roundup, but reaching into his briefcase he found a copy of the paper he had written with Erdos. Turan handed the paper to the soldier, who, duly impressed that Turan has been published in a Soviet journal, let him go. Turan later dryly reported this story to Erdos as a “surprising application of number theory.”
* my added comment: as in ID