#include<bits/stdc++.h>
using namespace std;
#define int long long
void solve()
{
	int a,b,c;
	cin>>a>>b>>c;
	int x=1,ans=c*b,cnt=0,num=0;
	while(x<=100*c)
	{
		cnt=c/x*b+num;
		if(c%x!=0)cnt+=b;
		//if(c%b!=0)cnt+=b;
		ans=min(ans,cnt);
		x*=2;
		num+=a;
		//cnt=c/x*b;
		//ans=min(ans,cnt+num);
	}
	cout<<ans;
}
signed main()
{
	int t;
	cin>>t;
	while(t--)
	solve();
	return 0;
 }