1. Six people sit in a row. Left to right, they are numbered 1 through 6.

2. Person 1 can stand up or sit down whenever he or she chooses to. All the other people can change their position (sit down or stand up) only if that person’s neighbor to their right (with the next lower number) is standing, and all the people to the neighbor’s right are seated.

3. So, for instance, if person 4 is standing, but 3,2, and 1 are all seated, then person 5 can stand up (or sit down). 1 2 3 4 5 6

4. And if person 4 is standing, and person 2 is also standing, but persons 1 and 3 are seated, person 5 cannot stand up: 1 2 3 4 5 6 …but person 3 can stand up.

5. And if persons 4 and 5 are standing, but all the others seated, then person 5 can sit down. 1 2 3 4 5 6 (And person 1 can stand up. But no one else can do anything else.)

6. The object of this group exercise is to get person 6 to stand up, with the others seated. 1 2 3 4 5 6