Why can we say that $n! = 1 \cdot 2 \cdot... \cdot \frac{n}{2} \cdot ... \cdot n$?

Question

Why can we say that $$n! = 1 \cdot 2 \cdot 3 \cdot ...\cdot \frac{n}{2} \cdot..\cdot n$$

I understand that $$5! = 5\cdot4\cdot3\cdot2\cdot1$$ but how can a $$\frac{n}{2}$$ appear when we say $$n!$$