Solving Charlemagne's brainteasers

Charlemagne liked a challenge, and he believed that the youth of his empire should be challenged as well. For that reason he commissioned an English scholar named Alcuin to compile Problems to Sharpen the Young, a collection of puzzles and brainteasers.

Two of Charlemagne's puzzles have been included in a new book by anthropology professor Marcel Danesi entitled The Total Brain Workout, and quoted in an article in the science section of the New York Times. Solvers can contact the professor with their answers for the chance to win a prize.