#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=1-1.0/x;        for(int i=0;i<b;i++)            cnt*=a;        cnt=1.0-cnt;        sum=(1+x)*x/2.0;        double ans=sum*cnt;        printf("Case #%d: %.3lf\n",c-t,ans);    }    return 0;}