If you know only the age of an American, there is some associated probablilty that he or she will live at least another year. E.g., 40 year-olds might have a 99.7% chance to make it another year.
How old are those Americans for whom there is less than an even money chance they will live another year?
It's easy to google up an actual answer, but it's far more interesting to approximate it from general facts you already know. Those general facts: There are about 300 million Americans. There are maybe 20,000 Americans in their early 100's. There are a few still alive in the 110's. And, grim but surprisingly true: Death rate keeps significantly increasing year after year.
When I found the actual figures, it surprised me how the death rate keeps increasing for all the very high recorded years. I had expected that it would go more asymptotic by somewhere long before the highest recorded age -- because I felt that the human organism is already so superannuated at some point that it's probably encountering all the possible problems of aging at near maximal rates...I was wrong, it's all downhill from there.
So, pencils & papers ready. Go!