#include <bits/stdc++.h>
using namespace std;

void print(vector<long long>& v){
    for(int i = v.size()-1; 0 <= i; --i) cout << v[i] << " ";
    cout << endl;
}
int main() {
    int Q; cin >> Q;
    while(Q--){

        long long A,B,C; cin >> A >> B >> C;

        if(C==1){
            cout << -1 << endl;
            continue;
        }

        if(A<C){
            cout << B << endl;
            return 0;
        }

        vector<long long> v;
        while(A>0){
            v.push_back(A%C);
            A /= C;
        }
        
        reverse(v.begin(),v.end());
        long long ans = 0;
        ans += (int)v.size() - 1;
        for(int i = 0; i < v.size(); ++i) if(v[i]) ans += 1;
        cout << ans*B << endl; 
    }
    return 0;
}