2-7

#include<stdio.h>
int main(void)
{
    int i,n,sum;


     printf("Enter n:");   
     scanf("%d",&n);      
     sum=0;                 
     for(i=1;i<=n;i++){           
         sum=sum+i;      
   
     printf("Sum of numbers from l to%d is %d\n",n,sum);

     return 0;
}