description: Theofanis really likes sequences of positive integers, thus his teacher (Yeltsa Kcir) gave him a problem about a sequence that consists of only special numbers.
  
  Let's call a positive number special if it can be written as a sum of different non-negative powers of n. For example, for n = 4 number 17 is special, because it can be written as 4^0 + 4^2 = 1 + 16 = 17, but 9 is not.
  
  Theofanis asks you to help him find the k-th special number if they are sorted in increasing order. Since this number may be too large, output it modulo 10^9+7.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases.
  
  The first and only line of each test case contains two integers n and k (2 ≤ n ≤ 10^9; 1 ≤ k ≤ 10^9).
  
  Output
  
  For each test case, print one integer — the k-th special number in increasing order modulo 10^9+7.
  
  Example
  
  Input
  
  
  3
  3 4
  2 12
  105 564
  
  
  Output
  
  
  9
  12
  3595374
  
  Note
  
  For n = 3 the sequence is [1,3,4,9...]
solution: import java.util.*;
  
   public class GFG {
      public static void main(String[] args)
      {
          Scanner sc = new Scanner(System.in);
          int t=sc.nextInt();
          while(t-->0)
          {
             int n=sc.nextInt();
             int k=sc.nextInt();
             long sum=0;
             String s=(Integer.toBinaryString(k));
             
             for(int i=s.length()-1;i>=0;i--)
             {
                 char ch=s.charAt(i);
                 if(ch=='1')
                 {
                     long m=1;
                     for(int j=0;j<s.length()-1-i;j++)
                     m=(m*n)%1000000007;
                     
                     sum=sum+m;
                 }
             }
             
  
          //   while(k>0){
          //       long x=log2(k);
          //       System.out.println(x);
          //       sum=(sum+(long)Math.pow(n,x)%1000000007)%1000000007;
          //       k=k-(int)Math.pow(2,x)%1000000007;
          //   }
             System.out.println(sum%1000000007);
          }
  
  
      }
      public static int log2(int N)
      {
    
          // calculate log2 N indirectly
          // using log() method
          int result = (int)(Math.log(N) / Math.log(2));
    
          return result;
      }
  }
  