#include<bits/stdc++.h>

using i64 = long long;

void DAOQI() {
    i64 a, b, c;
    std::cin >> a >> b >> c;
    i64 now = 1, ans = 1e18;
    for (int i = 0; i <= 30; i++) {
        ans = std::min(((c - 1) / now + 1) * b + i * a, ans);
        now *= 2;
    }
    std::cout << ans << "\n";
}

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int T = 1;
    std::cin >> T;
    while (T--) DAOQI();
    return 0;
}