#include <bits/stdc++.h>
#define int long long
#define re register
#define inf 0x3f3f3f3f
#define N 10202000
using namespace std;
const int mo=998244353;
inline int read(){
    int x=0,w=0;char ch=getchar();
    while (!isdigit(ch))w|=ch=='-',ch=getchar();
    while (isdigit(ch))x=(x<<1)+(x<<3)+ch-'0',ch=getchar();
    return w?-x:x;
}
double a[10][10];
int p[20];
signed main(){
	int T=read();
	while (T--){
		int n=read();
		for (int i=1;i<=n;++i)
			for (int j=1;j<=n;++j)
				scanf("%lf",&a[i][j]);
		for (int i=1;i<=n;++i)p[i]=i;
		double ans=0;
		do{
			double x=1;
			for (int i=1;i<=n;++i)x*=a[i][p[i]];
			ans+=x;
		}while (next_permutation(p+1,p+1+n));
		for (int i=1;i<=n;++i)ans/=i;
		printf("%.10lf\n",ans);
	}
    return 0;
}