The Kaprekar Routine

The Universal Constant

The Kaprekar constant 6174 is reached by repeatedly:

1. Taking any 4-digit number (at least two different digits).
2. Sorting the digits in descending and ascending order to get two numbers.
3. Subtracting the smaller from the larger.
4. Repeating for the new result.

The Assignment

Your function receives a 4-digit num.

1. Use a while loop that runs as long as the current result is not 6174.
2. Inside:
   • Extract the 4 digits and sort them.
   • Calculate the difference.
   • Print the difference.
3. The loop stops when 6174 is hit.