#include <iostream>
using namespace std;
#include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <cmath>
#include <cstring>

using ll = long long;

ll a, b, c;

void solve()
{
	cin >> a >> b >> c;
	ll now = 0;
	ll ans = c * b;
	ll ren = 1;
	while (ren < c)
	{
		now += a;
		ren *= 2;
		ans = min(ans, (ll)ceil((double)c / ren) * b + now);
	}
	cout << ans << '\n';
}

int main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int T = 1;
	cin >> T;
	while (T--)
	{
		solve();
	}
	return 0;
}