In essence, it is to turn a practical problem into a problem of finding the "least common multiple" through analysis, that is, to turn a practical problem into a mathematical problem, which is one of the manifestations of mathematical ability.
2. Combination of numbers and shapes
The idea of the combination of number and shape is to make full use of "shape" to express a certain quantitative relationship vividly. That is, by making some graphs such as line segment, tree diagram, rectangular area diagram or set diagram, students can correctly understand the quantitative relationship and make the problem concise and intuitive.
3. Change your mind Change your mind from one form to another.
4. The idea of combinatorial thinking is to group the studied objects reasonably and solve all possible situations one by one without repetition or omission. For example: