**Problem :-**Write A C++ Program To Find Sum Of The Following Series 1+2+3+4+5+6 . . . . . n .

**Logic :-**This is very simple series you just need to print sum of 1 to n terms ,there are two method you can use either use for loop or use formula Running time of using formula is

**Constant**or Running time of using

**for loop**is O(n) in words ' Order of N '

**Method 1:-**sum of series from 1 to N.

Formula =n(n+1)/2

**Method 2:-**sum of series from 1 to N.

for(i=1;i<=n;++i)

{

sum+=i;

}

If you are interested then you can modified this series for large number or you can try below series .

Try Yourself C++ Program To Find Sum Of The Given Series 1/2+4/5+7/8+ . . . N

**Solution :-**

Method 1:- Using For Loop

#include<iostream>

using namespace std;

int main()

{

//By-Ghanendra Yadav

int i,n,sum=0;

cout<<"\n1+2+3+4+5+6+……+n\n";

cout<<"\nEnter The Value Of N:\n";

cin>>n;

for(i=1;i<=n;++i)

{

sum+=i;

}

cout<<"\nSum = "<<sum<<endl;

return 0;

}

Method 2:- Using Formula

#include<iostream>

using namespace std;

int main()

{

//By-Ghanendra Yadav

int i,n,sum=0;

cout<<"\n1+2+3+4+5+6+……+n\n";

cout<<"\nEnter The Value Of N:\n";

cin>>n;

sum=(n*(n+1))/2;

cout<<"\nSum = "<<sum<<endl;

return 0;

}

**Output:-**

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