Quick, think of a number from 1 to 20. Did you pick 17? Okay, that trick doesn’t always work—but if you ask people to pick a number between 1 and 20, 17 is the most common choice. And if you ask people for a number between 0 and 9, they most frequently pick 7. Numbers ending in 0 and 5, by contrast, are chosen much more rarely than chance would lead you to expect—they just seem less random to people.
