A fun game you can play with your entire class. The teacher picks a number, and writes it down on a piece of paper. Everybody else then picks their own numbers (one each) and write it on a piece of paper, with their name attached. The ballots are then compared. The person with the biggest number wins, unless the total of all the numbers is bigger than the number the teacher picked, in which case everybody loses. Best played iteratively, like the prisoner's dilemma, with the teacher varying the range of numbers from 2 to 613 to c.