Summaries of Chapters 7-9

Chapter 7-

The chapter begins with Roberts mother talking to herself with Robert in the room. His mother sends him outside but he returns for dinner and goes to bed. The number devil takes Robert to a little white house shaped like a cube with no furniture. All it had in it was plastic looking electronic cubes. The number devil and Robert build a large triangle. After it is built they number the triangles with how many cubes on top of each one. 

The number devil clapped his hands after they were done, and one row would light up. Robert would have to add up the numbers on the cubes of each row. The next time the number devil clapped the triangle numbers lit up. Then the numbers divisible by five, and them Bonacci numbers. The chapter ends with the lights going out, and the number devil growing very thin. 

Chapter 8-

The chapter begins with Robert in his class room with his friends. the number devil walks in instead of his normal teacher. In this chapter the number devil teaches that you can find how many possibilities there are for his eleven classmates to shake hands with each other and how many seating arrangements with triangle numbers. The chapter ends with the number devil going on a holiday, and Robert going to school.

Chapter 9-

Chapter nine begins with Robert being sick with the flu. He eventually falls asleep and dreams that he is sick with the flu, but the number devil is there. He is there with an army of people in different color shirts with numbers on them. He tells the numbers to get in rows. The rows are types of numbers they have talked about. 

The number devil teaches Robert about series. He teaches him about the fractions in a series too. The chapter ends with the number devil growing thinner and thinner.