$\displaystyle\lim_{n\to\infty} \dfrac{1}{n!} = 0$
I have no idea how to proceed with this. Usually I start with a preliminary computation and solve for $n$ in terms of $\epsilon$ from the definition of the limit:
$|\dfrac{1}{n!} - 0| < \epsilon$
Here, I do not see an approach to solve for n.