#include <stdio.h>
#include <math.h>
int main () {
    int T, cs = 1;
    scanf("%d", &T);
    for (cs = 1; cs <= T; cs++) {
        double a, b;
        scanf("%lf %lf", &a, &b);
        if (b>2*a-b) b = 2*a-b;

        printf("Case %d: %.6lf\n", cs, ((a/2)*(a/2) - (a*a)/4 +b*b)/(a/2 - b) * ((a/2)*(a/2) - (a*a)/4 +b*b)/(a/2 - b));
    }
    return 0;
}