Methods and means to solve problems through calculation and analysis of mathematical models. According to the inquiry of Lele class, the number of paths is a method to solve problems through mathematical model calculation and analysis. In mathematics, math mainly involves using mathematical theories, skills and methods to deduce and prove mathematical propositions, solve practical problems and optimize schemes. Several paths can be used in various fields, such as engineering, physics, economy and so on, to help people better understand and explain phenomena and develop new theories and applications. Path number plays an important role in scientific research and practice.