What will be the upper bound of covering number of $r B_{n}^2$

Question

I am very curious to know The covering numbers of the r-radius Euclidean ball $B_{n}^2$ for any $r$ > 0: so $r B_{n}^2$ is a Euclidean ball with radius $r$

Have read this but unable to find.

Can anyone kindly tell What will be the upper bound for this case.