#include <iostream>
#include <cmath>
#include <iomanip>
#define PI 3.1415926535897932385
#define min(a,b) ((a)<(b)?(a):(b))
 
using namespace std;
 
int main()
{
    int t;
    cin >> t;
    while(t--)
    {
        double w,h;
        cin >> w >> h;
 
        double r1 = w/(2.0*PI);
        double h1 = h - 2.0*r1;
        double r2 = min(h/(2.0*(PI+1.0)),w/2.0);
        double h2 = w;
        double v1 = PI*r1*r1*h1;
        double v2 = PI*r2*r2*h2;
        cout << setprecision(12) << fixed << (v1>v2?v1:v2) << endl;
    }
 
    return 0;
}
 

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