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

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int q;
	cin >> q;
	vector<ll> n(q);
	vector<ll> k(q);
	rep(i, q) cin >> n[i] >> k[i];
	vector<ll> ans(q);
	rep(i, q) {
		ll res = 1;
		ll sol = n[i];
		if (k[i] == 1) { ans[i] = n[i] - 1; continue; }
		while (1) {
			sol -= res;
			res *= k[i];
			if (sol > 0) ans[i]++;
			else break;
		}
	}
	rep(i, q) cout << ans[i] << endl;
}