#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <math.h>
#include <assert.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <functional>
#include <vector>
#include <deque>
#include <utility>
#include <bitset>
#include <limits.h>
using namespace std;
typedef long long ll;
typedef unsigned long long llu;
typedef double lf;
typedef unsigned int uint;
typedef long double llf;
typedef pair<int, int> pii;
typedef pair<ll, int> pli;
#define memset0(x) memset(x, 0, sizeof (x));
int TC, TCC;
double C, X, F;
void init () {
}
void solve () {
scanf("%lf%lf%lf", &C, &F, &X);
lf res = X / 2;
for(int farms = 0; farms < 2000; farms++) {
if(farms * F + 2.0 > X) break;
lf t = 0, r = X;
for(int i = 0; i < farms; i++) t += C / (i * F + 2.0);
t += r / (farms * F + 2.0);
res = min(res, t);
}
printf("Case #%d: %.10lf\n", TCC, res);
}
int main() {
scanf("%d", &TC);
while(++TCC <= TC) {
init();
solve();
}
return 0;
}
