Binomial distribution

Tossing a coin $n$ times, how likely to get $k$ heads?

$n$
$p$
$$p(k) = \begin{cases} {n \choose k}p^k(1-p)^{n-k}, & \text{if k = 0, 1, \cdots, n,} \\ 0, & \text{otherwise.} \end{cases} \\[16pt] \text{where p is the probability the coin lands on heads.}$$