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

int main() {
    int q;
    cin >> q;
    rep(query, q) {
        ll a, b, c;
        cin >> a >> b >> c;
        if(c == 1) {
            cout << -1 << endl;
            continue;
        }
        vector<int> d;
        while(a > 0) {
            d.push_back(a % c);
            a /= c;
        }
        ll ans = 1000;
        for(int i = (int)d.size() - 1; i >= 0; i--) {
            ll sum = i, tmp = 0;
            for(int j = (int)d.size() - 1; j >= i; j--) {
                tmp *= c;
                tmp += d[j];
            }
            for(int j = i - 1; j >= 0; j--) {
                if(d[j]) sum++;
            }
            sum += tmp / (c - 1);
            if(tmp % (c - 1)) sum++;
            ans = min(ans, sum);
        }
        cout << ans * b << endl;
    }
    return 0;
}