#include "bits/stdc++.h"
using namespace std;
typedef long long int ll;
typedef vector<ll> vl;
typedef pair<ll, ll> P;
#define rep(i,n) for(ll i = 0; i < ll(n); i++)
#define all(v) v.begin() , v.end()
#define inputv(v,n) rep(i,n){\
    ll x;\
    cin>>x;\
    v.push_back(x);\
    }
const ll INF = 99999999999999;
const ll MOD = 1000000007;
ll a, b, c, d, e, f, p, q, t, k, m, n, ans = 0;
vl N, K;

void input(void) {
	cin >> q;
}

void solve(void){
	while (q--) {
		cin >> n >> k;
		if (k == 1) {
			cout << n - 1 << endl;
		}
		else {
			a = 1;
			ans = -1;
			while (n > 0) {
				n -= a;
				a = a * k;
				ans++;
			}
			cout << ans << endl;
		}
	}
}
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	input();
	solve();
}