This thing is relatively simple. His principle is that, for example, if the number you choose is X, you can actually return to X through a series of complicated operations. In other words, his seemingly complicated steps can actually be simplified by simplification.
However, the last time I was in the park, I saw a liar. His circular cardboard divides the circle into dozens of parts with a straight line centered on the center of the circle. Some wrote numbers, some wrote many rewards, and there was only one result, with a fine of 5 yuan. He asked you to sift a number with a sieve, then began to walk clockwise in the grid where the number was written, and finally judged the reward and punishment. But in the end, you can find that no matter how you screen, you have passed.
In other words, every number of his figures, no matter how many, can get the same result through calculation. In fact, he just led all the possible results together through clever design.