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 long long mod = 1e9 + 7;
  long long power(int a, int b) {
    long long ans = 1;
    for (int i = 0; i < b; i++) ans = (ans * a) % mod;
    return ans;
  }
  void doo() {
    int n, k;
    cin >> n >> k;
    long long res = 0;
    for (int i = 31; i >= 0; i--) {
      if (k & (1 << i)) {
        res += power(n, i);
        res %= mod;
      }
    }
    cout << res << '\n';
  }
  signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int tt;
    cin >> tt;
    while (tt--) doo();
    return 0;
  }
  