Germany: 167 1 year, Gottfried Wilhelm Leibniz of Germany invented the mechanical calculator, which was used for addition, subtraction, multiplication and division in early mathematical monographs. It was discovered by archaeologists in the Han bamboo slips unearthed in Zhangjiashan, Jiangling, Hubei Province in 1984. Zhou Bingsuan was written in the late Western Han Dynasty. Although it is an astronomical work on the theory of covering the sky, it contains two mathematical achievements-(1), a special case or universal form of Pythagorean theorem ("If you seek evil to the sky, take the sun as a sentence and the sun as a copy, multiply each sentence separately and divide it by the formula, you will get evil to the sky." -This is the earliest written record of Pythagorean theorem in China); (2) Chen Zi's method of measuring the height or distance of the sun. Nine Chapters Arithmetic plays a very important role in the development of ancient mathematics in China. It was compiled by many people and written in the Eastern Han Dynasty. This book * * * collects 246 math problems and provides their answers. The main contents include four fractional and proportional algorithms, the calculation of various areas and volumes, and the calculation of pythagorean measurement. In algebra, Nine Chapters Arithmetic put forward the concept of negative number and the law of addition and subtraction of positive and negative numbers for the first time in the history of world mathematics. The solution of linear equations taught in middle school is basically the same as that introduced in Chapter 9 Arithmetic. Paying attention to practical application is a remarkable feature of nine chapters arithmetic. Some knowledge of the book has also spread to India and Arabia, and even to Europe through these areas. The Southern and Northern Dynasties witnessed the vigorous development of ancient mathematics in China, and many books about mathematics appeared, such as Sun Tzu's Calculations, Xiahou Yang's Calculations and Zhang Qiu's Calculations. The most representative works in this period are the works of Zu Chongzhi and Zuxuan. Focusing on mathematical thinking and reasoning, they took a step forward on the basis of Liu Hui's Notes on Nine Chapters of Arithmetic. According to historical records, his book seal script (Yi) has achieved the following achievements: ① Pi is accurate to the sixth place after the decimal point, which is 3. 14 15926.