# Chiliagon Number

• Last Updated : 13 Apr, 2021

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

A chiliagon number is class of figurate number. It has 1000 – sided polygon called chiliagon. The N-th chiliagon number countâ€™s the 1000 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few chiliagonol numbers are 1, 1000, 2997, 5992 …

Examples:

Input: N = 2
Output: 1000
Explanation:
The second chiliagonol number is 1000.
Input: N = 3
Output: 2997

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

• Nth term of s sided polygon =
• Therefore Nth term of 1000 sided polygon is

Below is the implementation of the above approach:

## C++

 // C++ program for above approach#include using namespace std; // Finding the nth chiliagon Numberint chiliagonNum(int n){    return (998 * n * n - 996 * n) / 2;} // Driver Codeint main(){    int n = 3;    cout <<"3rd chiliagon Number is = "         << chiliagonNum(n);     return 0;} // This code is contributed by shivanisinghss2110

## C

 // C program for above approach#include #include  // Finding the nth chiliagon Numberint chiliagonNum(int n){    return (998 * n * n - 996 * n) / 2;} // Driver program to test above functionint main(){    int n = 3;    printf("3rd chiliagon Number is = %d",           chiliagonNum(n));     return 0;}

## Java

 // Java program for the above approachclass GFG{ // Finding the nth chiliagon numberstatic int chiliagonNum(int n){    return (998 * n * n - 996 * n) / 2;} // Driver codepublic static void main(String[] args){    int n = 3;    System.out.println("3rd chiliagon Number is = " +                                    chiliagonNum(n));}} // This code is contributed by rutvik_56

## Python3

 # Python3 program for above approach # Finding the nth chiliagon Numberdef chiliagonNum(n):     return (998 * n * n - 996 * n) // 2; # Driver Coden = 3;print("3rd chiliagon Number is = ",                  chiliagonNum(n)); # This code is contributed by Akanksha_Rai

## C#

 // C# program for the above approachusing System;class GFG{ // Finding the nth chiliagon numberstatic int chiliagonNum(int n){    return (998 * n * n - 996 * n) / 2;} // Driver codepublic static void Main(){    int n = 3;    Console.Write("3rd chiliagon Number is = " +                               chiliagonNum(n));}} // This code is contributed by Akanksha_Rai

## Javascript

 
Output:
3rd chiliagon Number is = 2997

Time Complexity: O(1)

Auxiliary Space: O(1)

Reference: https://en.wikipedia.org/wiki/Chiliagon

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