Required Mathematical Intelligence

Chapter 7 Go Upstairs
The office building where I work and the family building where I live both have 6 floors, while the floors where I work and live are both on 3 floors.So I thought: What fraction of the number of steps I climb every day is that of my colleagues who live on the 6th floor and work on the 6th floor?

[Answer: If you don't think about it, it is easy to draw a conclusion of one-half, but this conclusion is wrong.The key here is that people who live on the first floor don't need to climb stairs.If you want to go to the third floor, you need to climb two steps, not three, and if you want to go to the sixth floor, you have to climb five steps instead of six.Answer: two out of five. ]
(End of this chapter)