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Sum of natural numbers 1 to n in C++ language|5 ways
In this tutorial, we will discuss the concept of C++ program to the sum of Natural number from 1 to n – (n is entered number)
In this post, we are going to learn how to find the sum of natural numbers of C++ language in different 5 ways

Addition of natural numbers 1 to n – using for loop
Program 1
#include <iostream>
#include <conio.h>
using namespace std;
int main()
{
int sum=0,num,i;
cout<<"Enter a natural number\n";
cin>>num;
for(i=1; i<=num; i++){
sum+=i; //sum=sum+i;
}
cout<<"Sum of natural numbers from 1 to "<<num<<": "<<sum;
getch();
return 0;
}
When the above code is executed it produces the following output
Enter a natural number 25 Sum of natural numbers from 1 to 25: 325
This program allows the user to enter a maximum number. and it displays the addition of natural numbers from 1 to given number using for loop in C++ language
Addition of natural numbers 1 to n – using while loop
Program 2
#include <iostream>
#include <conio.h>
using namespace std;
int main()
{
int sum=0,num,i;
cout<<"Enter a natural number\n";
cin>>num;
i=1;
while(i<=num){
sum+=i; //sum=sum+i;
i++;
}
cout<<"Sum of natural numbers from 1 to "<<num<<": "<<sum;
getch();
return 0;
}
When the above code is executed it produces the following output
Enter a natural number 50 Sum of natural numbers from 1 to 50: 1275
This program allows the user to enter a maximum number. and it displays addition of natural numbers from 1 to given number using while loop in C++ language
Addition of natural numbers 1 to n – using do-while loop
Program 3
#include <iostream>
#include <conio.h>
using namespace std;
int main()
{
int sum=0,num,i;
cout<<"Enter a natural number\n";
cin>>num;
i=1;
do{
sum+=i; //sum=sum+i;
i++;
}while(i<=num);
cout<<"Sum of natural numbers from 1 to "<<num<<": "<<sum;
getch();
return 0;
}
When the above code is executed it produces the following output
Enter a natural number 30 Sum of natural numbers from 1 to 30: 465
This program allows the user to enter a maximum number. and it displays addition of natural numbers from 1 to given number using the do-while loop in C++ language
Addition of natural numbers 1 to n – using function
Program 4
#include <iostream>
#include <conio.h>
using namespace std;
int sumNaturalnum(int);
int main()
{
int num,sum=0;
cout<<"Enter a natural number\n";
cin>>num;
sum=sumNaturalnum(num);
cout<<"The sum of natural numbers 1 to"<<num<<": "<<sum;
getch();
return 0;
}
int sumNaturalnum(int n){
if(n==0)
{
return n;
}
else{
return (n*(n+1)/2);
}
}
When the above code is executed it produces the following output
Enter a natural number 40 Sum of natural numbers from 1 to 40: 820
This program allows the user to enter a maximum number. and it displays Addition of natural numbers from 1 to given number using function in C++ language
Addition of natural numbers 1 to n – using recursive function
Program 5
#include <iostream>
#include <conio.h>
using namespace std;
int sumNaturalnum(int);
int main()
{
int num,sum=0;
cout<<"Enter a natural number\n";
cin>>num;
sum=sumNaturalnum(num);
cout<<"The sum of natural numbers 1 to "<<num<<": "<<sum;
getch();
return 0;
}
int sumNaturalnum(int n){
if(n==0)
{
return n;
}
else{
return (n+sumNaturalnum(n-1));
}
}
When the above code is executed it produces the following output
Enter a natural number 200 Sum of natural numbers from 1 to 200: 20100
This program allows the user to enter a maximum number. and it displays addition of natural numbers from 1 to given number using recursive method in C++ language
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