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

typedef long long LL;

void solve(){
	LL a, b, c; cin >> a >> b >> c;
	LL ans = 1e18;
	for (int k = 0; (1ll << k) <= 2 * c; k++){
		LL selves = (1ll << k);
		LL round = (c + selves - 1) / selves;
		LL cost = k * a + round * b;
		ans = min(ans, cost);
	}
	cout << ans << endl;
}

int main(){
	ios :: sync_with_stdio(false), cin.tie(0);
	int T;
	for (cin >> T; T--; solve());
	return 0;
}