Zhu Zaiyu calculated the square root and square root with an extra-large abacus spanning 8 1 file, put forward the theory of "variable diameter tube", and designed and manufactured the chord quasi-harmonic tube on this basis. Zhu Zaiyu's "Twelve Average Laws" make the increase and decrease of every two adjacent keys of these twelve keys equal. After decades of painstaking research, Zhu Zaiyu finally solved the academic problems left over from this music scene for more than 1000 years with his twelve-average law theory. Once the law of twelve averages appeared, 89% of the world's musical instrument pronunciation and theoretical standards were based on the law of twelve averages. For example, the piano, known as the "king of musical instruments", was invented according to the principle of twelve equal laws. Perhaps this kind of professional vocabulary in music confuses us, so let's quantify it: up to now, nine of the ten musical instruments in the world are tuned on the basis of the twelve-average law, which is generally regarded as "standard tuning" and "standard western temperament" in the west today.