Step 1:

If you take any three digit number excluding the ones with 3 same
digits , say you choose 512.

Step 2:


Then you rearrange this number to get the maximum and minimum number
represented by these digits which will be 521 and 125 respectively.
Subtracting the smallest from the largest would yield 396

You now repeat Step 2 with the number you had from subtraction

963 - 369=594


Back to Step 2:

954-459=495

If you try these steps with any three digit number, given that all
three digits are not same; you will end up with 495 if you go through
the procedure in step 2.

For four digit numbers, the process terminates at 6174

The procedure does not terminate at any special number for numbers
with more than 4 digits

Website: http://www.BritishComputerColleges.com/VU/polaRgraphs.html

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