Possible Duplicate:
bijective map from $\mathbb{R}^3\rightarrow \mathbb{R}$
I know it's possible to produce a bijection from $\mathbb{Z}$ to $\mathbb{Z}\times\mathbb{Z}$, but is it possible to do so from $\mathbb{R}$ to $\mathbb{R} \times \mathbb{R}$?