#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int Q, N, K;
ll cnt, p;

int main() {
  cin >> Q;
  while (Q--) {
    cin >> N >> K;
    if (K == 1) {
      cout << N - 1 << endl;
      return 0;
    }
    cnt = 0;
    for (int i = 0;; i++) {
      p = 1;
      for (int j = 0; j < i; j++) {
        p *= K;
      }
      cnt += p;
      if (cnt >= N) {
        cout << i << endl;
        break;
      }
    }
  }
  return 0;
}