rt，思路感觉和题解一样啊……

//程序算法：数学，模拟
#include <bits/stdc++.h>
#define int long long
using namespace std;

struct Fraction{
	int p,q;       //分子，分母
	Fraction operator + (const Fraction& rhs) const {
		int ansp=p*rhs.q+rhs.p*q;
		int ansq=q*rhs.q;
		return (Fraction){ansp/__gcd(ansp,ansq),ansq/__gcd(ansp,ansq)};
	}
};

ostream& operator << (ostream &out,const Fraction& x){
	out<<x.p<<'/'<<x.q;
	return out;
}

void fast_read()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
}

signed main()
{
	//freopen("input.in","r",stdin);
	//freopen("output.out","w",stdout);
	
	fast_read();
	
	int T;
	cin>>T;
	for(int kase=1;kase<=T;kase++)
	{
		int s;
		cin>>s;
		Fraction ans={0,1};
		for(int i=1;i<=s;i++)
		{
			int x;
			cin>>x;
			ans=ans+(Fraction){1,x};
		}
		int p=ans.p,q=ans.q;
		ans={q*s,p};
		cout<<"Case "<<kase<<": "<<ans<<endl;
	}
	return 0;
}