100 Numerical Games

Follow the hour hand and minute hand of a clock for 24 hours. How many times do they form a right angle?
Timothy's house has several rooms, each of which has an even number of doors, including doors that lead outside. Is the number of outside doors even or odd?
Stimulating and delightful, this collection of puzzles features original and classic brainteasers. The author, a puzzle columnist for Le Monde, specially selected these mind-benders for the widest possible audience, ensuring that they'...