Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
C++ Program to Calculate Sum of Natural Numbers
The natural numbers are the positive integers starting from 1.
The sequence of natural numbers is −
1, 2, 3, 4, 5, 6, 7, 8, 9, 10……
Sum of the first n natural numbers can be calculated using the for loop or the formula.
Programs specifying both of these methods are given as follows −
Sum of Natural Numbers Using for loop.
The program to calculate the sum of n natural numbers using for loop is given as follows.
Example
#include<iostream>
using namespace std;
int main() {
int n=5, sum=0, i;
for(i=1;i<=n;i++)
sum=sum+i;
cout<<"Sum of first "<<n<<" natural numbers is "<<sum;
return 0;
}Output
Sum of first 5 natural numbers is 15
In the above program, a for loop is run from 1 to n. In each iteration of the loop, the value of i is added to the sum. So, the sum of the first n natural numbers is obtained. This is demonstrated by the following code snippet.
for(i=1;i<=n;i++) sum=sum+i;
Sum of Natural Numbers using Formula
The formula to find the sum of first n natural numbers is as follows.
sum = n(n+1)/2
The program to calculate the sum of n natural numbers using the above formula is given as follows.
Example
#include<iostream>
using namespace std;
int main() {
int n=5, sum;
sum = n*(n+1)/2;
cout<<"Sum of first "<<n<<" natural numbers is "<<sum;
return 0;
}Output
Sum of first 5 natural numbers is 15
In the above program, the sum of the first n natural numbers is calculated using the formula. Then this value is displayed. This is demonstrated by the following code snippet.
sum = n*(n+1)/2; cout<<"Sum of first "<<n<<" natural numbers is "<<sum;
2K+ Views
