#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int,int> ii;

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

    ll q, n, k;
    cin >> q;
    for (int ctr1 = 0; ctr1 < q; ++ctr1) {
        cin >> n >> k;
        if (k == 1) {
            cout << n - 1 << "\n";
            continue;
        }
        ll cur = 1, rez = 0;
        while (n > cur) {
            n -= cur;
            cur *= k;
            ++rez;
        }
        cout << rez << "\n";
    }

    return 0;
}