#include<bits/stdc++.h>
using namespace std;
#define IOS ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);


using ll = long long;
#define int ll
#define endl "\n"
#define no cout << "NO" << endl
#define yes cout << "YES" << endl
#define pb push_back
#define mkp make_pair
#define fi first
#define se second
#define ary(i) array<ll,(i)>
#define all(x) x.begin(),x.end()
const int maxn=2e5+7;
const int inf=1e9+7;
const int mod=998244353;


void solve(){
    int a,b,c;
    cin>>a>>b>>c;
    int mintime =  inf;
    int k=1;
    int t=0;
    while (k<2*c){
        int t1=t+c/k*b+ (c%k!=0)*b;
        mintime=min(mintime,t1);
        k*=2;
        t+=a;
    }
    cout<<mintime<<endl;


}

#undef int



int main()
{
    IOS
    int n;
    cin>>n;
    // n=1;
    while(n--){
        solve();
    }

}