Are there more 11 digit or 12 digit palindromic numbers?

Answer 1

There are more 12-digit palindromic numbers than 11-digit palindromic numbers. This is because the number of possible 12-digit palindromic numbers is greater than the number of possible 11-digit palindromic numbers. In general, the number of palindromic numbers of length n is 9 * 10^((n-1)/2), so for 11-digit palindromic numbers, there are 9 * 10^5 = 900,000 possibilities, while for 12-digit palindromic numbers, there are 9 * 10^6 = 9,000,000 possibilities.

Answer 2

There are the same number: any twelve digit palindrome is just an eleven digit palindrome with its central digit repeated. In general, if we are considering numbers of n digits: For even values of n, the number of palindromes is 9 x 10n/2 - 1 For odd values of n, the number of palindromes is 9 x 10(n-1)/2