#include <bits/stdc++.h>
//#include <iostream>
#include <atcoder/all>
#include <math.h>
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rrep(i, n) for(int i = (n-1); i >= 0; i--)
using namespace std;
using namespace atcoder;
typedef long long ll;
const int MOD = 1000000007;
//const int MOD =  998244353;
 
const ll INF = 1LL<<61;
const int IINF = 1000000000;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

typedef pair<int, int> PI;
typedef pair<ll, ll> P;
typedef pair<string, ll> PS;

using mint = modint1000000007;

#include <regex>
int main(){

    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int Q; cin >> Q;
    vector<ll> N(Q), K(Q);
    rep(i,Q) cin >> N[i] >> K[i];

    vector<ll> ans(Q);
    rep(i,Q){
        ll n = N[i]-1;
        ll k = K[i];
        if (k == 1){
            ans[i] = n;
            continue;
        }
        ll a = 0;
        while(n > 0){
            n -= k;
            k *= K[i];
            a++;
        }
        ans[i] = a;
    }

    rep(i,Q){
        cout << ans[i] << endl;
    }
}