#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll qpow(ll a,ll b){
    ll ans=1;
    while(b>0){
        if(b&1)ans*=a;
        a*=a;
        b>>=1;
    }
    return ans;
}
void solve(){
    ll a,b,c,cur=1,ans=1e18;
    cin>>a>>b>>c;
    int cnt=0;
    while(cur<=c)cur<<=1,cnt++;
    for(int i=0;i<=cnt;i++){
        ll now=qpow(2,i),res=i*a;
        res+=(c/now+(c%now!=0))*b;
        ans=min(ans,res);
    }
    cout<<ans<<'\n';
    return void();
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t=1;
    cin>>t;
    while(t--){
        solve();
    }
    return 0;
}