#### Answer

6

#### Work Step by Step

The product rule for radicals tells us that $\sqrt[n] a\times\sqrt[n] b=\sqrt[n] ab$ (when $\sqrt[n] a$ and $\sqrt[n] b$ are real numbers and $n$ is a natural number). That is, the product of two nth roots is the nth root of the product.
Therefore, $\sqrt 12\times\sqrt 3=\sqrt (12\times3)=\sqrt 36=6$.
We know that $\sqrt 36=6$, because $6^{2}=36$.