Starting from some integers, after repeated iterations, the result will inevitably fall into the operation result of one point or several points. Digital black hole refers to a mathematical term and an algorithm, which refers to the operation result that starts from some integers and after repeated iterations, the result will inevitably fall into one point or several points. This concept comes from a black hole in astronomy. A black hole is a celestial body with such a powerful guiding force that even light cannot escape. In mathematics, this word is borrowed to describe the cyclic characteristics of some numbers or sequences under certain operations.