#include<bits/stdc++.h>
#define int long long
using namespace std;
int a,b,c;
signed main(){
    int t;
    cin>>t;
    while(t--){
        cin>>a>>b>>c;
        int num=1;
        int sum=0;
        int ans=((c-1)/num+1)*b;
        while(((c-1)/(num*2)+1)*b+sum+a<=ans){
            num*=2;
            sum+=a;
            ans=((c-1)/num+1)*b+sum;
        }
        cout<<ans<<endl;
    }
}