As we know the symbol $n$ determines the dimension of $\mathbb{R}^n$ in the category of vector spaces. Also, in the category of manifolds, $n$ determines the dimension of $n$-manifold $\mathbb{R}^n$.
Now, my question is that:
Is there any algebraic property related to the additive group $(\mathbb{R}^n ,+)$ which is determined by $n$?