# Enneacontagon Number

Given a number N, the task is to find Nth Enneacontagon number.

A Enneacontagon number. is class of figurate number. It has 90 – sided polygon called enneacontagon. The N-th enneacontagon number count’s the 90 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few enneacontagonol numbers are 1, 90, 267, 532 …

Examples:

Input: N = 2
Output: 90
Explanation:
The second enneacontagonol number is 90.

Input: N = 3
Output: 267

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: The N-th enneacontagon number is given by the formula:

• Nth term of s sided polygon = • Therefore Nth term of 90 sided polygon is Below is the implementation of the above approach:

## C++

 // C++ program for above approach  #include  using namespace std;     // Finding the nth enneacontagon Number  int enneacontagonNum(int n)  {      return (88 * n * n - 86 * n) / 2;  }     // Driver Code  int main()  {      int n = 3;      cout << "3rd enneacontagon Number is = "          << enneacontagonNum(n);         return 0;  }     // This code is contributed by Akanksha_Rai

## C

 // C program for above approach  #include  #include     // Finding the nth enneacontagon Number  int enneacontagonNum(int n)  {      return (88 * n * n - 86 * n) / 2;  }     // Driver program to test above function  int main()  {      int n = 3;      printf("3rd enneacontagon Number is = %d",             enneacontagonNum(n));         return 0;  }

## Java

 // Java program for above approach  class GFG{     // Finding the nth enneacontagon number   public static int enneacontagonNum(int n)   {       return (88 * n * n - 86 * n) / 2;   }      // Driver code      public static void main(String[] args)  {      int n = 3;          System.out.println("3rd enneacontagon Number is = " +                                       enneacontagonNum(n));  }  }     // This code is contributed by divyeshrabadiya07

## Python3

 # Python3 program for above approach      # Finding the nth enneacontagon Number   def enneacontagonNum(n):          return (88 * n * n - 86 * n) // 2    # Driver Code  n = 3 print("3rd enneacontagon Number is = ",                     enneacontagonNum(n))     # This code is contributed by divyamohan123

## C#

 // C# program for above approach  using System;  class GFG{     // Finding the nth enneacontagon number   public static int enneacontagonNum(int n)   {       return (88 * n * n - 86 * n) / 2;   }      // Driver code   public static void Main(String[] args)  {      int n = 3;          Console.WriteLine("3rd enneacontagon Number is = " +                                      enneacontagonNum(n));  }  }     // This code is contributed by Rajput-Ji

Output:

3rd enneacontagon Number is = 267


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