//#include<bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cmath>
#include <iomanip>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const ll base = 37;//进制
const ll mod = 998244353;//质数
const int inf = 1e9+5;
const int maxn = 5e6+5;
const ll linf = 1e18+5ll;
int main()
{
    cin.tie(NULL);
    cout.tie(NULL);
    ios::sync_with_stdio(false);
    int t;
    cin>>t;
    while(t--)
    {
        ll a,b,c;
        cin>>a>>b>>c;
        ll ans = linf;
        for(ll i = 1;i<=c*2;i*=2)
        {
            ll cost = (int)log2(i)*a + ceil(c*1.0/i)*b;
            ans = min(ans,cost);
        }
        cout<<ans<<endl;
    }
}