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: #include <bits/stdc++.h>
  using namespace std;
  const double PI = acos(0) * 2.0;
  const long long INF = 1e18L + 5;
  long long int mod = 1e9 + 7;
  void tc() {
    long long int n, k;
    cin >> n >> k;
    long long int p = 1;
    long long int ans = 0;
    for (long long int i = 0; i <= 31; i++) {
      if (k & 1) {
        ans = (ans % mod + p % mod) % mod;
      }
      p = ((p % mod) * (n % mod)) % mod;
      k /= 2;
    }
    cout << ans << endl;
  }
  int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long int t = 1;
    cin >> t;
    while (t--) {
      tc();
    }
  }
  