Funny arithmetic

What is interesting about mathematics? Where is the beauty of mathematics? Many children with poor grades inevitably have such doubts in their hearts.
Arithmetic games, in various forms such as theorems, interesting questions, and even unsolved mysteries, lead everyone to explore a corner of the mathematical world.
Play and do, let more children experience the magic of mathematics and truly fall in love with this fun filled subject.

contain
The number black hole 495 (three digit number),
The digital black hole 6174 (four digit number),
Quick calculation of special multiplication,
Double again, double again,
The number of palindromes,
A Little Magic (Number Prediction).