First, ask questions. This semester, I learned about math black holes in math textbooks. Mathematical black hole refers to the situation that natural numbers fall into a cycle after some mathematical operation. Moreover, four different numbers are needed to form a maximum and minimum number, and the result obtained by subtracting the minimum number from the maximum number does not exceed 7 steps, and the final answer must be 6 174. So I thought, are there black holes in numbers 2 to 5? Second, research ideas

Study whether there is a black hole from two digits to five digits.

Third, the research process

I first found two numbers 12, and combined them into the maximum number 2 1 and the minimum number 12, and then combined them into 21-kloc-0/2 = 9. I thought that a set of numbers could not prove a mathematical black hole, so I found two numbers 34 and synthesized them into a maximum value. So I can judge that the double-digit mathematical black hole must be 9.

After confirming the two digits, I'll find the three digits. I found the three numbers 246, which were divided into the largest and smallest three digits respectively. First, I make 642-246=396, then 396 becomes a maximum number 963, then a minimum number 369, and then 963-369=594. Then I repeated the previous steps. So I am sure that the three-digit black hole is 495.

I found five numbers, four, and made them the largest and smallest numbers respectively: 12345 and 5432 1, and then subtracted them to make them equal to 4 1976, and then made 4 1976 into 9764 1 and/kloc-. I decided to try again. I combined 82465 into the maximum number 86542 and the minimum number 24568, and then subtracted it, which is equal to 6 1974. Then I synthesize 6 1974 into 9764 1 and 14679, and then subtract it, which is equal to 82962. Then I repeated the previous steps. I know that the five-digit black hole is 6 1974.

I found: 2, 3 and 5 all have mathematical black holes. 、

Four. Research conclusion

I find mathematics actually very interesting, such as this mathematical black hole. After finding the pattern, it will be very interesting.