Legend has it that in ancient Greek mythology, Sisyphus, king of Corinth, was punished for pushing a boulder all the way to the mountain, but no matter how hard he tried, the boulder always rolled down before reaching the top of the mountain, so he had to push it again and never stopped. The world-famous String of Sisyphus is named after this story.

What is a Sisyphus string? It is an arbitrary number, such as 35962. By counting the numbers of even and odd numbers and all the numbers in this number, we can get 2(2 even numbers), 3(3 odd numbers) and 5 (five numbers in total), and use these three numbers to form the next number string 235. Repeat the above process with 235 to get 1, 2, 3. Repeating the sequence of 123 will still get 123. 123 is a mathematical black hole for this "universe" composed of programs and numbers.

Does every number end with 123? Try with a large number. For example: 88883377499222, in this number, even, odd and all numbers are 1 1, 9 and 20 respectively. When these three numbers are combined, you can get 1 1920. For 1 1920.

This is the famous mathematical black hole "Sisyphus string". Students study hard and discover the mystery!