:date: 2024-05-30 12:34

.. Tags for the index
.. index:: 6174

.. .. seealso:: :ref:

.. Reference for linking into the menues.
.. _2024-6174:

6174
====

The number `6174`_, or Kaprekar's, constant is interesting.

It will automatically show up when you do the following:

1. Take a four digit number with at least two different digits (allowing leading zeros).
2. Arrange the digits descending and ascending to two four digit numbers. Add leading zeros is required.
3. Subtract the smaller number from the bigger number.
4. Repeat from the second step.

If you do this a repeated number of times, you will come to 6174 in at most 7 iterations. From 6174 there is no way out.

Let's e.g. take 8664.

.. code:: bash

   8664 - 4668 = 3996
   9963 - 3699 = 6264
   6642 - 2466 = 4176
   7641 - 1467 = 6174
   7641 - 1467 = 6174

.. _`6174`: https://en.m.wikipedia.org/wiki/6174