P^2+Σ2P

This is e^-x. You may have 10 heads in each 10 times. P(X=10)=9.765625E-4≒9/10000 This is about 0.09%, and it is almost Zero. This is Poisson distribution. p = λ / n This is called Poisson limit theorem, and binomial distribution is Bernoulli trial. x=1000 heads, n=1000 times, p=0.5(heads or tails), f=9.33E-302 ∴