Talk about the reasons why abacus is listed as intangible cultural heritage.

Abacus is a method of digital calculation with abacus as a tool, which is known as the fifth invention of China. The meaning of abacus is far more than "fast". In Zhang Dehe's view, abacus is a calculation tool closest to the essence of "number". In the prehistoric times of "knotting notes", "number" was concrete; After the generalization of Arabic numerals, "number" is an abstract concept. Abacus just skillfully combines concreteness and abstraction: on the one hand, it is composed of beads, which is very intuitive; At the same time, it also contains abstract basic mathematical rules such as cumulative number and carry. If carefully studied, abacus calculation contains a vast mathematical world. Therefore, Zhang Dehe believes with confidence that as long as mathematics exists, abacus calculation has its value.