Multiple choice general knowledge math & puzzles

take any 4 digit number, arrange it in ascending order, arrange in descending order, keep on substracting them. after n substraction a constant number comes(n may be any +ve int depending on the input number). what is it?

  1. 6199

  2. 4259

  3. 3257

  4. 6174

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This refers to Kaprekar's constant for 4-digit numbers. If you repeat the process of subtracting the smallest number from the largest number formed by the digits, you will always eventually reach 6174. The other numbers provided are not fixed points for this algorithm.