九，无疑是一个计数单位，居个位数之末，为最大个位数。算学多用其归类或命名，如“九九”（乘法口诀）、“九归”（除法口诀）等。我国古代最早的一部数学典籍即名为《九章算术》，共九卷列九种算法类别。因而作为实数，“九”在世界各民族文字、文化中的意义和功能是差... Nine is undoubtedly a counting unit, the last digit, the largest single digits. Learn more with their classification or naming, such as “nine nine” (multiplication formula), “nine return” (divides the formula) and so on. In ancient China, one of the earliest mathematics classics is called “Nine Chapters of Arithmetic”, and there are nine volumes of nine kinds of algorithms. Therefore, as a real number, the meaning and function of “nine” in the languages ​​and cultures of all ethnic groups in the world are poor ...