>[!citation] >Looney, O. (2024, February 25). *Kaprekar's magic 6174*. OWL. https://www.oranlooney.com/post/kaprekar/ >[!abstract] >Kaprekar’s routine is a simple arithmetic procedure which, when applied to four digit numbers, rapidly converges to the fixed point 6174, known as the [[Kaprekar's constant|Kaprekar constant]]. Unlike other famous iterative procedures such as the [[Collatz function]], the somewhat arbitrary nature of the Kaprekar routine doesn’t hint at fundamental mathematical discoveries yet to be made; rather, its charm lies in its intuitive definition (requiring no more than elementary mathematics,) its oddly off-center fixed point of 6174, and its surprisingly rapid convergence (which requires only five iterations on average and never more than seven.)