In an underground passageway somewhere near Shinjuku, there is a machine that cleans your glasses.
A hot-air balloon that can carry 8 people costs “all your money”. Or if you prefer, about a hundred thousand dollars.
You can write a regular expression that matches only strings of a composite number of x's. (Hint: Too easy for a hint.)
I knew that Galileo discovered the first four of Jupiter's moons, the Galilean moons. I didn't know that the fifth known moon wasn't discovered until almost 300 years later, when Tennesseean E. E. Barnard discovered Amalthea.