Arithmetic is the oldest and most basic part of mathematics. It studies the properties and operations of numbers, which is one of the oldest branches of mathematics and one of the "starting points" of mathematics. The emergence of the concept of numbers and the formation of preliminary arithmetic operations can be traced back to prehistoric times. China developed arithmetic very early in ancient times and was the first country in the world to adopt decimal system.

There were several counting methods in ancient China: writing, calculating strategies and four operations. Including heavenly stems and earthly branches, which we are familiar with now, was originally a counting method. Since the emphasis is on counting, its expressions will naturally go through many development and replacement, and it is far from enough to speculate on its origin.

China ancient mathematics formed a unique application system very early, and the 99 multiplication table used to calculate addition, subtraction, multiplication and division was very popular in the Warring States Period. And Nine Chapters Arithmetic is also a typical representative. There is a complete fractional algorithm in "Nine Chapters Arithmetic". The proportional problem and profit and loss problem are studied and the corresponding algorithm is given.

The rules and concrete calculation methods of square root operation are given. The addition and subtraction rules of positive and negative numbers are given. Later, Liu Hui annotated the book, further used decimals, and put forward some new methods to calculate fractions and proportions. Zhang Qiujian Jing and Sun Zi Jing studied indefinite equations.

From the latter problem, the world-famous results of Sun Tzu's theorem and the unique algorithm of great derivation have been developed. There are many decimal methods and calculation methods in Numerology Notes, one of which is similar to modern methods. Approximating an important numerical value with fractions is also a famous arithmetic achievement of China in ancient times.

Not only has it developed in the application field of mathematics, but China's ancient world view, such as the theory of covering the sky and the theory of muddy the sky, is also based on the numerical calculation of the universe model created by the ancients. For example, Zhou Bi suan Jing, the oldest existing mathematical document in China, constructs a cosmological model of classical astronomy by calculating the positions and operating rules of cosmic celestial bodies.