1. The problem is to simplify $\sqrt{216}$.\n\n2. Recall that $\sqrt{a \times b} = \sqrt{a} \times \sqrt{b}$ and that we want to find perfect square factors of 216.\n\n3. Factor 216 into its prime factors: $216 = 2^3 \times 3^3$.\n\n4. Group the factors into pairs for simplification: $\sqrt{216} = \sqrt{2^3 \times 3^3} = \sqrt{(2^2 \times 3^2) \times (2 \times 3)}$.\n\n5. Apply the square root to each group: $\sqrt{(2^2 \times 3^2)} \times \sqrt{2 \times 3} = (2 \times 3) \times \sqrt{6} = 6 \sqrt{6}$.\n\n6. Therefore, the simplified form of $\sqrt{216}$ is $6 \sqrt{6}$.