Dover Publications is offering a free sample chapter from The Moscow Puzzles.
Cat and Mice
Purrer has decided to take a nap. He dreams he is encircle by 13 mice: 12 gray and 1 white. He hears his owner saying: “Purrer, you are to eat each thirteenth mouse, keeping the same direction. The last mouse you eat must be the white one.”
Denise Gaskins' Let's Play Math 