#include <bits/stdc++.h>

using i64 = long long;

constexpr i64 INF = 1e18;

void solve()
{
	int a, b, c; std::cin >> a >> b >> c;

	i64 ans = INF;
	for(i64 i = 0; (1 << i) <= 2 * c; i++)
		ans = std::min(ans, i * a + (c + (1 << i) - 1) / (1 << i) * b);
	
	std::cout << ans << "\n";
}

int main()
{
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);

	int t; std::cin >> t;
	while(t--) solve();

	return 0;
}