# 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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