Taking preparation for the take off contest.

G_Summing_Series.c

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

int main()
{
	int t,i;

	scanf("%d", &t);

	for(i=0; i<t; i++)
	{

       long double n,j,first_intry,last_entry,differ,sum, sum2=0;
       unsigned long long int result;
       scanf("%llf", &n);

       first_intry = 1;

       last_entry = pow(n,2)- pow(n-1,2);
       differ = 2;

	     //calculating sum with the help of formula of series.
       sum = (n/2)*(first_intry+last_entry);


       result = (unsigned long long int)sum%((unsigned long int)pow(10,9)+7);
		
	//printing sum and result to debug the programe.
       printf("%llf\t%llu\n",sum,result);



	}

	return 0;
}