Kaprekar's Constant

Professor D. R. Kaprekar discovered some wonderful facts about number 6174. According to his name, 6174 is known as Kaprekar’s Constant. Let’s consider a four digit number. Suppose the number is 3124.

   Step 1: Arrange your considered number digits in descending form. You will get 4321.

   Step 2: Now reverse the number, you got in step 1. That will be 1234.

   Step 3: Subtract step 2 result from step 1. Your answer  will be (4321 – 1234) = 3087.

   Step 4: Arrange step 3 result in descending form. That will be 8730.

   Step 5: Now reverse step 4 result. You will get 0378 or 378.

   Step 6: Substract step 5 result from step 4. You will get (8730 – 378) = 8352.

   Step 7: Arrange step 6 result in descending form. That will be 8532.

   Step 8: Now reverse step 7 result. You will get 2358.

   Step 9: Substract step 8 result from step 7. You will get (8532 – 2358) = 6174

And you are done! 6174 is your answer.