#include <iostream>
using namespace std;

int main(){
  int Q;
  cin >> Q;
  while(Q--){
    long long N, K;
    cin >> N >> K;
    if(K == 1){
      cout << N-1 << endl;
      continue;
    }
    long long t = 1, ans = 0;
    --N;
    while(N > 0) t *= K, N -= t, ++ans;
    cout << ans << endl;
  }
}