#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
const ull mod = 1e9 + 7;
#define REP(i,n) for(int i=0;i<(int)n;++i)

//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

template<class S, class T> ostream& operator << (ostream& os, const pair<S, T> v){
  os << "(" << v.first << ", " << v.second << ")"; return os;
}
template<class T> ostream& operator << (ostream& os, const vector<T> v){
  for(int i = 0; i < v.size(); i++){if(i > 0){os << " ";} os << v[i];} return os;
}
template<class T> ostream& operator << (ostream& os, const vector<vector<T>> v){
  for(int i = 0; i < v.size(); i++){if(i > 0){os << endl;} os << v[i];} return os;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll Q;
    cin >> Q;
    while(Q--){
    	ll N, K;
    	cin >> N >> K;
    	if(K==1){
    		cout << N-1 << endl;
    	}else{
	    	ll X = 1+N*(K-1);
	    	ll res = 0;
	    	while(X>0) X /= K, res++;
	    	cout << res-1 << endl;
	    }
    }
    return 0;
}