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

int main()
{
    int Q;
    cin >> Q;
    while (Q--) {
        ll N, K;
        cin >> N >> K;
        if (K == 1) {
            cout << N - 1 << endl;
            continue;
        }
        ll cnt = 0;
        ll siz = 1;
        while (N > 0) {
            N -= siz;
            siz *= K;
            cnt++;
        }
        cout << cnt - 1 << endl;
    }
    return 0;
}