The headline crops up every so often, one about the "oldest person in the world" dying. But only a mathematician or someone in a macabre betting pool would wonder exactly how often, and that's what prompted the site Stackexchange to put the question to its math-loving readership. The site ended up with several dizzying formulas—"for each age a, the number of people of age a in year t is the fraction of the population aged a−1 at time t−1 who don’t die, i.e.N(t,a) (1−h(a−1))×N(t−1,a−1)"—but most answers boiled to somewhere around 0.65 years, reports the Smithsonian.
"Now, obviously, figuring out who the oldest person in the world is, is pretty hard," writes Rose Eveleth. "But since most of us will never hold the title of oldest person in the world, we can at least savor the fact that, for at least a few seconds, we were at one point the youngest."