#include<iostream>

#include<cstdio>

#include<cmath>

using namespace std;

int main()

{

    int t;scanf("%d",&t);

    int c=t;

    while(t--){

        long long x;

        int b;

        double cnt=1.0;

        long long sum;

        scanf("%lld%d",&x,&b);

        double a=-1.0/x;

        for(int i=;i<b;i++)

            cnt*=a;

        cnt=1.0-cnt;

        sum=(+x)*x/2.0;

        double ans=sum*cnt;

        printf("Case #%d: %.3lf\n",c-t,ans);

    }

    return ;

}