#include<iostream>
#include<cmath>
#define ll long long
#define int long long
using namespace std;
int Q;
signed main(){
	cin>>Q;
	while(Q--){
		ll ans=0;
		int n,k,g;
		cin>>n>>k>>g;
		ll sum=k*g;
		int temp=ceil(g/2);
		ll x=sum-(n-1)*(temp-1);
		if(x<=0){
			cout<<sum<<endl;
			continue;
		}
		ans+=(n-1)*(temp-1);
		ll r=x%g;
		if(r>=temp)ans+=(r-g);
		else ans+=r;
		cout<<ans<<endl;
	}
}