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68 arithmetic/digits/palindrome.p




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This article is from the Puzzles FAQ, by Chris Cole chris@questrel.questrel.com and Matthew Daly mwdaly@pobox.com with numerous contributions by others.

68 arithmetic/digits/palindrome.p


Does the series formed by adding a number to its reversal always end in
a palindrome?

arithmetic/digits/palindrome.s

This is not known.

If you start with 196, after 9480000 iterations you get a 3924257-digit
non-palindromic number. However, there is no known proof that you will
never get a palindrome.

The statement is provably false for binary numbers. Roland Sprague has
shown that 10110 starts a series that never goes palindromic.

 

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