from random import randint
n , s , c = 0 , 0 , 0
for i in range(1,1001):
    while s == 0 and n < 10:
        e = randint(1,6)
        if e == 6: s = 1
        n += 1
        if n == 10: c += 1
    n , s = 0 , 0
print(c / 1000)