Answer
$0$
Work Step by Step
We need to apply ratio test for a given series.
$\lim\limits_{n \to \infty} |\dfrac{a_{n+1}}{a_n}|=\lim\limits_{n \to \infty} |\dfrac{(n+1)!}{n!} |=\infty$
This implies that the radius of convergence of the series is $0$ and the series converges for $x=0$.
