/* -*- coding: utf-8 -*-
 *
 * 897.cc:  No.897 comp留ctree - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

typedef long long ll;

/* global variables */

/* subroutines */

/* main */

int main() {
  int q;
  scanf("%d", &q);

  while (q--) {
    int n, k;
    scanf("%d%d", &n, &k);

    int d = 0;
    if (k == 1)
      d = n - 1;
    else {
      ll e = 1;
      while (n > e) {
	d++;
	n -= e;
	e *= k;
      }
    }

    printf("%d\n", d);
  }
  return 0;
}