#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> l_l;
typedef pair<int, int> i_i;
template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}

#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))
//const ll mod = 1000000007;
ll beki(ll a, ll b) {
    if(b == 0) return 1;
    ll ret = beki(a, b / 2);
    ret = ret * ret;
    if(b & 1) ret *= a;
    return ret;
}

void solve() {
    ll N, K;
    cin >> N >> K;
    if(K == 1) {
        cout << N - 1 << endl;
        return;
    }
    ll now = 0;
    for(int i = 0; ; i++) {
        now += beki(K, i);
        if(now >= N) {
            cout << i << endl;
            return;
        }
    }
}

int main() {
    //cout.precision(10);
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll Q;
    cin >> Q;
    while(Q--) solve();
    return 0;
}