#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	double a,b;
	for(int k=1;k<=n;k++){
		cin>>a>>b;
		a*=b;
		cout<<fixed<<setprecision(1)<<a/100*85<<endl;
	}
	return 0;
}