"The finishing touch of mathematical thinking" is a visual statement, which refers to the key point in solving mathematical problems. Through a simple and key step or idea, we can simplify the complex and make the whole problem easy to solve. Solving mathematical problems requires a variety of methods and skills, but sometimes some problems seem difficult and can be solved with a simple idea or skill. This kind of thinking or skill is often suddenly thought of in the process of solving, just like the "finishing touch", which instantly makes the problem clear and easy to understand. For example, when solving a geometric problem, you may need to use multiple geometric theorems and formulas, but you only need a key line segment or angle relationship to get the answer to the whole problem. This key line segment or angle relationship is "the highest point of mathematical thinking".