C/C++ Program to find sum of n natural numbers

//Program to find sum of n natural numbers
#include<iostream>
using namespace std;
int main()
{
    int n,sum;
    cout<<"\n enter a natual number:";
    cin>>n;
    sum=n*(n+1)/2;
    cout<<"\n sum of "<<n<<" natural numbers is : "<<sum<<endl;
return 0;
}

C/C++ Program to print hello world

//Program to print hello world
#include<iostream>
using namespace std;
int main()
{
    cout<<"\n HELLO! WORLD"<<endl;
return 0;
}

C/C++ Program to find FACTORS of a given number

//Program to find FACTORS of a given number
#include<iostream>
using namespace std;
int main()
{
    int a;
    cout<<"\n enter a positive number to find factors:";
    cin>>a;
    cout<<"\n Factors of "<<a<<endl;
    for(int i=1;i<=a;i++)
    {
        if(a%i==0)
          cout<<i<<" ";
    }
    cout<<endl;
return 0;
}

C/C++ Program to find a given number is STRONG (or) not.

//Program to find a given number is STRONG or not.
#include<iostream>
using namespace std;
int main()
{
       int a;
       cout<<"\n enter a number:";
       cin>>a;
       int i,f,r,sum=0,num;
       num=a;
       while(num>0)
        {
          i=1;f=1;
           r=num%10;
           while(i<=r)
                    {
            f=f*i;
            i++;
            }
        sum=sum+f;
        num=num/10;
           }
           if(sum==a)
        cout<<" Yes, "<<a<<" is a strong number."<<endl;
       else
        cout<<"No, "<<a<<"is not a strong number "<<endl;
return 0;
}   
            

C/C++ Program to find sum of digits of a given number

//Program to find sum of digits of a given number
#include<iostream>
using namespace std;
int main()
{
int a,r,num,sum=0;
cout<<"\n enter a number:";
cin>>a;
if(a<0)
    num=-a;
else
    num=a;
while(num>0)
{
    r=num%10;
    sum=sum+r;
    num=num/10;
}
if(a<0)   
    cout<<"\n sum of digits= -"<<sum<<endl;
else
    cout<<"\n sum of digits="<<sum<<endl;
return 0;
}

C/C++ Program to find prime number between 1 and n

//Program to find prime number between 1 and n
#include<iostream>
using namespace std;
int main()
{
 int n,m,i=2,is_prime=1;
 cout<<"enter up to which number you want to find prime numbers:";
 cin>>m;
 for(n=2;n<=m;n++)
        {
      for(i=2;i<n;i++)
        {
             if(n%i==0)   
                   {
                   is_prime=0;
               break;
                    }
            else
             is_prime=1;
        }
        if(is_prime)
            cout<<n<<" ";
    }
    cout<<endl;
return 0;
}
Similar program(s):
C++ Program to find a given number is Prime (or) not. 
C++ Program to find a given number is even (or) odd.
       

C/C++ Program to find a given number is even (or) odd.

// Program to find a given number is even (or) odd.
#include<iostream>
using namespace std;
int main()
{
int n,i,is_even=0;
cout<<"\n enter a number"<<endl;
cin>>n;
for(i=2;i<n;i++)
{
if(n%2==0)
    is_even=1;
}
if(is_even)
cout<<n<<" is an even"<<endl;
else
cout<<n<<" is an odd"<<endl;
return 0;
}