import sys
#sys.setrecursionlimit(10 ** 6)
INF = float('inf')
MOD = 10**9 + 7
MOD2 = 998244353
from collections import defaultdict
def ceil(A,B):
    return -(-A//B)
def solve():
    def II(): return int(sys.stdin.readline())
    def LI(): return list(map(int, sys.stdin.readline().split()))
    def LC(): return list(sys.stdin.readline().rstrip())
    def IC(): return [int(c) for c in sys.stdin.readline().rstrip()]
    def MI(): return map(int, sys.stdin.readline().split())
    T = II()
    for i in range(T):
        P,K = input().split()
        P = float(P)
        K = int(K)
        E = 0
        Q = 1
        if(P==1.0):
            print(1.00000000000)
        else:
            for k in range(1,K+1):
                E += Q*P*k
                Q*=(1-P)
            E+=Q*K
            print(E)
    return
solve()