T = int(input())
PK = [input().split() for _ in range(T)]
for p, k in PK:
    p = float(p)
    k = int(k)

    ans = 0
    for i in range(k-1):
        ans += (i+1)*(1-p)**i*p
    ans += k*(1-p)**(k-1)
    print(ans)