What is the cardinality of $\Bbb{N^N}$?
my answer: $|\mathbb{R}|$ $=$$|2^\mathbb{N}|$ $\leqslant$ $|\mathbb{N}^\mathbb{N}|$ $\leqslant$ $|\mathbb{R}^\mathbb{N}|$ $=$ $|(2^\mathbb{N})^\mathbb{N}|$ $=$ $|2^{\mathbb{N}\times\ \mathbb{N}}|$ $=$ $|2^\mathbb{N}|$ $=$ $|\mathbb{R}|$
In the end $|\mathbb{N}^\mathbb{N}|$ $=$ $|\mathbb{R}|$
Is that okay?
Yes. The answer is fine.
(Incidentally my students just have this question in their homework)