#include <bits/stdc++.h>

using namespace std;

int k, a, b, c;

double dp[][][][];

double dfs(int at, int x, int y, int z)

{

    if(dp[at][x][y][z]) return dp[at][x][y][z];

    double tmp = ;

    double fm = 1.0 * (x + y + z + 1.0);

    tmp += 1.0 / fm * (dfs(at - , x, y, z) + 1.0);

    if(x) tmp += 1.0 * x / fm * dfs(at - , x - , y, z);

    if(y)

    {

        if(x + y + z == ) tmp += 1.0 * y / fm * dfs(at - , x + , y - , z);

        else tmp += 1.0 * y / fm * dfs(at - , x + , y - , z + );

    }

    if(z)

    {

        if(x + y + z == ) tmp += 1.0 * z / fm * dfs(at - , x, y + , z - );

        else tmp += 1.0 * z / fm * dfs(at - , x, y + , z);

    }

    dp[at][x][y][z] = tmp;

    return tmp;

}

int main()

{

    int T;

    scanf("%d", &T);

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

        for(int j = ; j < ; j++)

        {

            if(i + j > ) continue;

            for(int k = ; k < ; k++)

            {

                if(i + j + k > ) continue;

                dp[][i][j][k] = 1.0 / (i + j + k + 1.0);

            }

        }

    while(T--)

    {

        scanf("%d%d%d%d", &k, &a, &b, &c);

        double ans = dfs(k, a, b, c);

        printf("%.2lf\n", ans);

    }

    return ;

}