On the first day, the mouse hit 1 foot, the mouse hit 1 foot, one ***2 feet, and there were 3 feet left;

The next day, the mouse hit two feet, and the mouse hit 1/2 feet. I hit 2.5 feet this day, 4.5 feet in two days, and 0.5 feet left;

On the third day, it is reasonable to say that the mouse hit 4 feet, and the mouse hit 1/4 feet. Now there is only 0.5 feet left, and it will definitely get through on the third day.

Chapter 9 Introduction to Arithmetic:

Nine Chapters Arithmetic is a mathematical monograph written by Zhang Cang and Geng Shouchang in ancient China. It is the most important of the ten computing classics, written about the first century A.D., and its author can no longer be examined. It is generally believed that it has gradually become the final version after several generations of supplement and modification. Zhang Cang and Geng Shouchang in the Western Han Dynasty had been supplemented and sorted out, and they were generally finalized at that time. The last book was in the early years of the Eastern Han Dynasty at the latest, and most of them were Notes to Nine Chapters written by Wei Yuan, Jing Yuan and Liu Hui in the Three Kingdoms Period (263).

"Nine Chapters Arithmetic" is very rich in content and summarizes the mathematical achievements in the Warring States, Qin and Han Dynasties. At the same time, Nine Chapters Arithmetic has its unique achievements in mathematics. It not only mentioned the problem of score at the earliest, but also recorded the problem of surplus and deficiency at the earliest. Zhang Equation also expounded the negative number and its addition and subtraction algorithm for the first time in the history of world mathematics. It is a comprehensive historical work and the most concise and effective applied mathematics in the world at that time. Its appearance marks the formation of a complete system of ancient mathematics in China.

Baidu Encyclopedia-Chapter 9 Arithmetic