A Palindromic Sum
This is a nut that has not yet been completely cracked.
Take any number. (Do not use algebra, just a natural number) Make any palindromic pair of it. Add the 2 numbers. Make a palindromic pair of the sum, and add the sum and its palindrome. Continue this process until the sum is palindromic. These are 2 examples:
17+71=88. 88 is a palindromic number.
104+401=505. 505 is a palindromic number.
I had to add them only once,didn't do anything with the first sum. But we can add them any number of times, unless the sum is palindromic.
Which of the following is a number that does not follow the rule of the palindromic sum?
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1 solution
Kind of hard to prove that 196 never reaches a palindromic number, although none happens after 10000 iterations. The longer the number, the less likely the next iteration will yield a palindrome.