text: #include<stdio.h>
  
  int main()
  {
      int n, i, sum =0;        
      printf("Enter a Natural number : ");    
      scanf("%d",&n);
      for(i=1; i <= n;++i)
      {        
          sum += i;
      }    
      printf("Sum = %d",sum);
      return 0;
  }
  
  ========
   Output
  ========
  
  Enter a Natural number : 100
  Sum = 5050
  