Someone else mentioned Hari Seldon in Asimov's Foundation Series, but there is also a wonderful Asimov short story in which the protagonist is a government mathematician who discovers, by analyzing primitive computers, how to do computations such as multiplication and division with only paper and pencil. (Actually, he may be writing on a pad, but anyway, he's doing it by hand.)
SPOILER ALERT (The rest of this post gives away some, but not all, of the plot.)
The point of the story is that no one on earth remembers how to do even arithmetic, everyone just relies on calculators and computers. The government becomes very interested in this discovery, because it has the potential to allow them to build war rockets piloted by people (inexpensive), rather than by computers (expensive). Given the extent to which children these days are taught to do arithmetic using calculators, Asimov's story is quite prescient. The only problem is that I don't remember the title, maybe someone on MO can help out with that.
