#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fast ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define For(i,aa,ac) for(int i=aa;i<=ac;i++)
int n,m;
const int N=2e6+7,INF=1e18;
int a,b,c,ans;
int p[50];
void solve(){
    ans=INF;
    cin>>a>>b>>c;
    For(i,0,31)
    {
        if(p[i]>=c)
        {
            ans=min(ans,i*a+b);break;
        }
        else{
            int bb=(c+p[i]-1)/p[i];
            ans=min(ans,i*a+b*bb);
        }
    }
    cout<<ans<<endl;
}
signed main(){
    fast;
    int t=1;
    p[0]=1;
    For(i,1,32)
        p[i]=2*p[i-1];
    cin>>t;
    while(t--){
        solve();
    }
}