



 
Pradip, It looks to me as if you are taking four digits a, b, c and d, constructing two numbers abcd and dbca, and then subtracting them. If this is correct then the numbers you have are
Subtracting the second from the first gives ( I am assuming a is larger than d so that the subtraction yields a positive number.)
Division by 9 yields
This is the digit a  d, repeated three times. A similar result will occur is you start with any positive integer with an even number of digits. I don't know how you are treating a positive integer with an odd number of digits. Harley  


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