using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var t = NN;
        var ans = new double[t];
        for (var u = 0; u < t; ++u)
        {
            var s = ReadLine().Split();
            var p = double.Parse(s[0]);
            var k = int.Parse(s[1]);
            var prob = 1.0;
            var sub = 0.0;
            for (var i = 1; i < k; ++i)
            {
                sub += prob * p * i;
                prob *= (1 - p);
            }
            ans[u] = sub + prob * k;
        }
        WriteLine(string.Join("\n", ans));
    }
}