Mathematical definition: refers to the use of designated symbols to represent various elements in nature, which have been understood and mastered by human beings through observation, recording and summary in practice. The result obtained after operation later represents a method of natural laws. 2. Function: The greatest function of understanding and mastering these natural laws is to predict the future. 3. Features: Unknown situations can only be calculated by known situations. 4. Features: Known situations must be represented by designated symbols. 5. Limitations: Special unknowns can only be calculated by special known situations. 6. inevitability: all unknowns can never be calculated by existing known situations. 7. Reason: The universe is infinite and infinitesimal. Infinity means nothing, everything is a cloud, and so is mathematics. It's just what human beings think is self-righteous and only useful to human beings. 8. For example, a circle is 360 degrees. How did it come into being? In fact, it is based on. Well, it took so many years to realize that this is actually math. 9. Conclusion: Mathematical knowledge, like history, is only the mark left by biological activities in nature!