#include <stdio.h>

using namespace std;

int N,R;

FILE * fout;

void Solve()
{
   int i=0, step=0;
   long nr =0;
   while (0==0)
   {
     if (step % 2==0)
     {
        i++;
        nr = nr+ i;

        if (nr-(nr-i+1)>= (N-1)*R)
        {
           fprintf(fout,"%d\n",(nr-i+1));
           return ;
        }
     } else
     {
        nr = nr +i;
     }
     step++;
   }
}

void ReadData()
{
    FILE * fin = fopen("progresie.in","r");
    fout = fopen("progresie.out","w");

    int T;
    fscanf(fin,"%d",&T);


    for (int i=0; i<T; i++)
    {
       fscanf(fin,"%d %d",&N, &R);
       Solve();
    }

    fclose(fin);
    fclose(fout);
}

int main()
{
    ReadData();
    return 0;
}