Find the sum of the following sequence : 2, 22, 222, ……… to n terms.
Examples :
Input : 2 Output: 1.9926 Input : 3 Output: 23.9112
A simple solution is to compute terms one by one and add to the result.
The above problem can be efficiently solved using the following formula:
C++
// CPP program to find sum of series // 2, 22, 222, .. #include <bits/stdc++.h> using namespace std; // function which return the // the sum of series float sumOfSeries(int n) { return 0.0246 * (pow(10, n) - 1 - (9 * n)); } // driver code int main() { int n = 3; cout << sumOfSeries(n); return 0; } |
Java
// JAVA Code for Sum of the // sequence 2, 22, 222,... import java.util.*; class GFG { // function which return the // the sum of series static double sumOfSeries(int n) { return 0.0246 * (Math.pow(10, n) - 1 - (9 * n)); } /* Driver program */ public static void main(String[] args) { int n = 3; System.out.println(sumOfSeries(n)); } } // This code is contributed by Arnav Kr. Mandal. |
Python3
# Python3 code to find # sum of series # 2, 22, 222, .. import math # function which return # the sum of series def sumOfSeries( n ): return 0.0246 * (math.pow(10, n) - 1 - (9 * n)) # driver code n = 3print( sumOfSeries(n)) # This code is contributed by "Sharad_Bhardwaj". |
C#
// C# Code for Sum of the // sequence 2, 22, 222,... using System; class GFG { // Function which return the // the sum of series static double sumOfSeries(int n) { return 0.0246 * (Math.Pow(10, n) - 1 - (9 * n)); } // Driver Code public static void Main() { int n = 3; Console.Write(sumOfSeries(n)); } } // This code is contributed by vt_m. |
PHP
<?php // PHP program to find sum // of series 2, 22, 222, .. // function which return the // the sum of series function sumOfSeries($n) { return 0.0246 * (pow(10, $n) - 1 - (9 * $n)); } // Driver Code $n = 3; echo(sumOfSeries($n)); // This code is contributed by Ajit. ?> |
Output :
23.9112
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