#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  int q;
  cin >> q;
  while (q--) {
    int n, k;
    cin >> n >> k;
    if (k == 1) {
      cout << n - 1 << '\n';
      continue;
    }
    long long cur = 0, c = 1;
    for (int i = 0; ; i++) {
      cur += c;
      if (cur >= n) {
        cout << i << '\n';
        break;
      }
      if (1. * c * k > 2e18) c = 1LL << 60;
      else c *= k;
    }
  }
  return 0;
}