T = int(input())
for t in range(T):
    p, K = map(float, input().split())
    K = int(K)
    prob = [0]*(K+1)
    cumu = 0
    for i in range(1, K+1):
        if i == K:
            prob[i] = 1-cumu
        else:
            prob[i] = (1-cumu)*p
        cumu += prob[i]
    EV = 0
    for i in range(1, K+1):
        EV += i*prob[i]

    #print(prob)
    print(EV)