Leibniz formula

A formula that gives an expression for the $n$-th derivative of the product of two functions in terms of their derivatives of orders $k=0,\dots,n$ (the derivative of order zero is understood to be the function itself). Namely, if the functions $u=u(x)$ and $v=v(x)$ have derivatives up to the order $s$ inclusive at some point, then at this point their product $uv$ has derivatives of the same orders, and for $n=0,\dots,s$,
$$(uv)^{(n)}=\sum_{k=0}^n\binom nku^{(k)}v^{(n-k)}.$$