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# Count of N-digit Palindrome numbers

• Last Updated : 10 Mar, 2022

Given an integer N, the task is to find the count of N-digit Palindrome numbers.
Examples:

Input: N = 1
Output:
{1, 2, 3, 4, 5, 6, 7, 8, 9} are all the possible
single digit palindrome numbers.
Input: N = 2
Output:

Approach: The first digit can be any of the 9 digits (not 0) and the last digit will have to be same as the first in order for it to be palindrome, the second and the second last digit can be any of the 10 digits and same goes for the rest of the digits. So, for any value of N, the count of N-digit palindromes will be 9 * 10(N – 1) / 2.
Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach``#include ``using` `namespace` `std;` `// Function to return the count``// of N-digit palindrome numbers``int` `nDigitPalindromes(``int` `n)``{``    ``return` `(9 * ``pow``(10, (n - 1) / 2));``}` `// Driver code``int` `main()``{``    ``int` `n = 2;` `    ``cout << nDigitPalindromes(n);` `    ``return` `0;``}`

## Java

 `// Java implementation of the approach``class` `GFG``{``    ` `// Function to return the count``// of N-digit palindrome numbers``static` `int` `nDigitPalindromes(``int` `n)``{``    ``return` `(``9` `* (``int``)Math.pow(``10``,``           ``(n - ``1``) / ``2``));``}` `// Driver code``public` `static` `void` `main(String []args)``{``    ``int` `n = ``2``;` `    ``System.out.println(nDigitPalindromes(n));``}``}` `// This code is contributed by Code_Mech`

## Python3

 `# Python3 implementation of the approach` `# Function to return the count``# of N-digit palindrome numbers``def` `nDigitPalindromes(n) :` `    ``return` `(``9` `*` `pow``(``10``, (n ``-` `1``) ``/``/` `2``));` `# Driver code``if` `__name__ ``=``=` `"__main__"` `:` `    ``n ``=` `2``;` `    ``print``(nDigitPalindromes(n));` `# This code is contributed by AnkitRai01`

## C#

 `// C# implementation of the approach``using` `System;``    ` `class` `GFG``{``    ` `// Function to return the count``// of N-digit palindrome numbers``static` `int` `nDigitPalindromes(``int` `n)``{``    ``return` `(9 * (``int``)Math.Pow(10,``           ``(n - 1) / 2));``}` `// Driver code``public` `static` `void` `Main(String []args)``{``    ``int` `n = 2;` `    ``Console.WriteLine(nDigitPalindromes(n));``}``}` `// This code is contributed by Rajput-Ji`

## Javascript

 ``

Output:

`9`

Time Complexity: O(log n)

Auxiliary Space: O(1)

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