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.io.*;
          import java.nio.charset.StandardCharsets;
          import java.util.*;
          import java.io.BufferedReader;
          import java.io.IOException;
          import java.io.InputStreamReader;
  
  public class Solution {
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(
                      new InputStreamReader(System.in));
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
      }
  
      public static void main(String[] args) throws Exception {
  
          BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new
                  FileOutputStream(java.io.FileDescriptor.out), StandardCharsets.US_ASCII), 512);
          FastReader sc = new FastReader();
          int[][] store = new int[31][2];
          store[0][0]=1;
          store[0][1]=1;
          for(int i=1;i<=30;i++){
              store[i][0]=(int)(Math.pow(2,i));
              store[i][1]=(int)(Math.pow(2,i+1)-1);
  
          }
          int m = (int)1e9+7;
          int z = sc.nextInt();
          while(z-->0) {
              int n = sc.nextInt();
              int k = sc.nextInt();
              long ans =0;
              while(k!=0){
  
                  for(int i =0;i<=30;i++){
                      if(k>store[i][1])
                          continue;
                      k-=store[i][0];
                      //System.out.println(k+" "+ i );
                      ans+= power(n,i);
                      ans%=m;
                      break;
                  }
              }
              out.write(ans+"\n");
          }
          out.flush();
      }
      static int power(int n , int pow ){
       int m = (int)(1e9+7);
       long ans =1;
       long mul = n;
       for(int i=pow;i>0;i/=2){
           if(i%2==1) {
               ans *= mul;
               ans %= m;
           }
  
               mul*=mul;
               mul%=m;
  
  
       }
       return (int)ans%m;
      }
  }
  
  
  
  
  
  