Palindromic numbers and reverse-and-add

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Learn it A palindromic number reads the same forwards and backwards, like 66, 121 or 4554. To find the next palindrome, keep the left half and mirror it; if that is too small, add 1 to the middle of the left half and mirror again. Reverse-and-add: add a number to its reverse; many numbers become palindromes after a few rounds.

Example: Reverse and add 57 until you get a palindrome.

57 + 75 = 132.
132 + 231 = 363, a palindrome, after 2 rounds.

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