#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int main() {
    int Q; cin >> Q;
    while (Q--) {
        LL N, K; cin >> N >> K;
        LL t = 1;
        LL ans = 0;
        if (K == 1) ans = N - 1;
        else {
            while (true) {
                N = max(0ll, N - t);
                if (N == 0) break;
                ans++;
                t *= K;
            }
        }
        cout << ans << endl;
    }

    return 0;
}