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#include<bits/stdc++.h>
using namespace std;
int main()
{
int n;
int sum=0;
cin>>n;
for(int i=1;i<=n;i++)
{
sum+=i;
}
cout<<sum<<" ";
cout<<endl;
return 0;
}
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//Created by https://ashif.in
#include <bits/stdc++.h>
using namespace std;
int main()
{
int n;
cin>>n; //Take Input
int sum = n*(n+1)/2; //Calculate Sum
cout<<sum; //Print Sum
return 0;
}
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Sum of the First n Natural Numbers. We prove the formula 1+ 2+ + n = n(n+1) / 2, for n a natural number