Why did China call "mathematics" "arithmetic" in ancient times?

In ancient China, "calculation" refers to a bamboo computing device, "arithmetic" refers to the technology of operating this computing device, and also refers to all the mathematical knowledge related to calculation at that time. The word "arithmetic" officially appeared in "Nine Chapters of Arithmetic". During the Sui and Tang Dynasties, the state set up a special institution to train astronomers and mathematicians-"Arithmetic", which is equivalent to the mathematics department in universities now. The teaching books include Sun Tzu's Arithmetic, Five Cao Arithmetic Classics and Nine Chapters Arithmetic. /kloc-since the 0/9th century, some western mathematics disciplines, including algebra and trigonometry, analytic geometry, calculus, probability theory, etc. , have been introduced to China. Most western missionaries used "mathematics", while China still used "arithmetic" in ancient times. 1935, chinese mathematical society established the meaning of "arithmetic", and arithmetic and mathematics still coexist. It was not until 1939 that Tsinghua University changed "Mathematics Department" to "Mathematics Department".