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120-gon number
• Last Updated : 16 Mar, 2021

Given a number N, the task is to find Nth 120-gon number.

A 120-gon number is a class of figurate numbers. It has 120 – sided polygon called 120-gon. The N-th 120-gon number count’s the 120 number of dots and all other dots are surrounding with a common sharing corner and make a pattern. The first few 120-gon numbers are 1, 120, 357, 712, 1185, 1776, …

Examples:

Input: N = 2
Output: 120
Explanation:
The second 120-gonol number is 120.
Input: N = 3
Output: 357

Approach: The N-th 120-gon number is given by the formula:

• Nth term of s sided polygon =

• Therefore Nth term of 120 sided polygon is

•

Below is the implementation of the above approach:

## C++

 // C++ implementation for above approach#include using namespace std; // Function to find the // nth 120-gon Numberint gonNum120(int n){    return (118 * n * n - 116 * n) / 2;} // Driver Codeint main(){    int n = 3;    cout << gonNum120(n);     return 0;}

## Java

 // Java program for above approachclass GFG{ // Function to find the// nth 120-gon Numberstatic int gonNum120(int n){    return (118 * n * n - 116 * n) / 2;} // Driver codepublic static void main(String[] args){    int n = 3;    System.out.print(gonNum120(n));}} // This code is contributed by shubham

## Python3

 # Python3 implementation for above approach # Function to find the# nth 120-gon Numberdef gonNum120(n):     return (118 * n * n - 116 * n) // 2; # Driver Coden = 3;print(gonNum120(n)); # This code is contributed by Code_Mech

## C#

 // C# program for above approachusing System;class GFG{ // Function to find the// nth 120-gon Numberstatic int gonNum120(int n){    return (118 * n * n - 116 * n) / 2;} // Driver codepublic static void Main(String[] args){    int n = 3;    Console.Write(gonNum120(n));}} // This code is contributed by sapnasingh4991

## Javascript


Output:
357

Reference: https://en.wikipedia.org/wiki/120-gon

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