The mysterious number 6174
Think of any 4 non-zero digits, where not all four digits are the same. Arrange the digits in descending order and ascending order and compute the difference. For instance, if the digits are 3,3,2 and 1,
Repeat the above step by rearranging the result into ascending and descending order and compute the difference.
The process terminates when the number reaches 6174. We can use another example,
and Viola! We get the same result again! Can you figure out why this happens?