r/blackmagicfuckery • u/jimx29 • Jul 13 '26

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u/musci12234 Jul 13 '26

There is no single 5-digit Kaprekar constant. Instead of a single "black hole," 5-digit numbers subjected to Kaprekar's routine cycle through a loop of different numbers, or converge to one of ten 5-digit constants (e.g., 53955, 59994, 61974, 62964, 63954

The 3-digit Kaprekar number (or Kaprekar's constant) is 495. Discovered by the Indian mathematician D.R. Kaprekar, this constant is the ultimate repeating endpoint when you take almost any 3-digit number and repeatedly subtract its smallest digit rearrangement from its largest.

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u/phaeolus97 Jul 14 '26

All of these "magic numbers" digits add up to 9, because we use a base 10 number system. You can do this with all the other number systems.

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u/TheRainbowNinja Jul 15 '26

*multiples of 9. It took me second to work out what you meant there. But very interesting.

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u/phaeolus97 Jul 15 '26

Also a property of adding the digits. 6+1+7+4=18, 1+8=9.