#include<bits/stdc++.h>
#define ll long long

using namespace std;

void solve()
{
    int a, b, c;
    cin >> a >> b >> c;
    int k = 1;
    ll res = 1ll * c * b, ans = 0;
    while (k < c)
    {
        ans += a, k *= 2;
        res = min(res, ans + 1ll * (c + k - 1) / k * b);
    }
    cout << res << '\n';
}

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