# Find the count of natural Hexadecimal numbers of size N

• Last Updated : 19 Mar, 2022

Given an integer N, the task is to find the count of natural Hexadecimal numbers with N digits.
Examples:

Input: N = 1
Output: 15
Input: N = 2
Output: 240

Approach: It can be observed that for the values of N = 1, 2, 3, …, a series will be formed as 15, 240, 3840, 61440, 983040, 15728640, … which is a GP series whose common ratio is 16 and a = 15.
Hence the nth term will be 15 * pow(16, n – 1).
So, the count of n-digit natural hexadecimal numbers will be 15 * pow(16, n – 1).
Below is the implementation of the above approach:

## C++

 `// C++ implementation of the above approach``#include ``using` `namespace` `std;` `// Function to return the count of n-digit``// natural hexadecimal numbers``int` `count(``int` `n)``{``    ``return` `15 * ``pow``(16, n - 1);``}` `// Driver code``int` `main()``{``    ``int` `n = 2;``    ``cout << count(n);``    ``return` `0;``}`

## Java

 `// Java implementation of the approach``class` `GFG``{` `// Function to return the count of n-digit``// natural hexadecimal numbers``static` `int` `count(``int` `n)``{``    ``return` `(``int``) (``15` `* Math.pow(``16``, n - ``1``));``}` `// Driver code``public` `static` `void` `main(String args[])``{``    ``int` `n = ``2``;``    ``System.out.println(count(n));``}``}` `// This code is contributed by 29AjayKumar`

## Python3

 `# Python3 implementation of the above approach` `# Function to return the count of n-digit``# natural hexadecimal numbers``def` `count(n) :` `    ``return` `15` `*` `pow``(``16``, n ``-` `1``);` `# Driver code``if` `__name__ ``=``=` `"__main__"` `:` `    ``n ``=` `2``;``    ``print``(count(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``    ``// natural hexadecimal numbers``    ``static` `int` `count(``int` `n)``    ``{``        ``return` `(``int``) (15 * Math.Pow(16, n - 1));``    ``}``    ` `    ``// Driver code``    ``public` `static` `void` `Main(String []args)``    ``{``        ``int` `n = 2;``        ``Console.WriteLine(count(n));``    ``}``}` `// This code is contributed by 29AjayKumar`

## Javascript

 ``

Output:

`240`

Time Complexity: O(log n)

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