factorial(20)/(factorial(4)* factorial(16))
choose(20, 4)

# ex 1

factorial(5)   # 120 Möglichkeiten

# ex 2
factorial(10)/(factorial(5) * factorial(2) * factorial(3))  # 2520

# ex 3
choose(15, 6)

factorial(15)/(factorial(6)*factorial(9)) # 5005

0.4*0.4+0.4*0.6+0.6*0.4
1 - 0.6*0.6