In this number game, 7th graders work as a class to figure out a three-digit mystery number. Students use logic and the process of elimination to find the answer. It is a great time filler when there are 10 minutes left in class, and once students learn the rules, they can lead the exercise themselves.In this number game, students work as a class to figure out a three-digit mystery number. Students use logic and the process of elimination to find the answer.