Kaprekar's constant (6174)

6174 is known as Kaprekar's constant after the Indian mathematician D. R. Kaprekar. This number is known for the following rule:

• Take any four-digit number (at least two digits should be different)
• Arrange the digits in descending and ascending order to get two new four-digit numbers
• Now, subtract the smaller number from the bigger number
• Go back to step 2 and repeat

This process is called Kaprekar's routine. The routine states that you'll always reach number 6174 in at most 7 iterations and once you reach 6174, the process will continue generating the same number. How cool is that?

Installation

Install directly from the GitHub repository

pip install git+https://github.com/shashankdeshpande/kaprekar_constant.git 

Usage

Import package:

>>> import kaprekar_constant as kc

Perform Kaprekar Routine:

>>> obj = kc.kaprekar_routine(1913)
>>> obj
<kaprekar_constant.object.Kaprekar at 0x7f1ae2f085c0>

Check results:

>>> obj.steps
['9311 - 1139 = 8172',
 '8721 - 1278 = 7443',
 '7443 - 3447 = 3996',
 '9963 - 3699 = 6264',
 '6642 - 2466 = 4176',
 '7641 - 1467 = 6174']
>>> obj.step_count
6
>>> obj.constant
6174

References

• https://en.wikipedia.org/wiki/6174_(number)
• https://mathworld.wolfram.com/KaprekarRoutine.html
• https://plus.maths.org/content/mysterious-number-6174