Multiple choice general knowledge math & puzzles The square root of 18 simplifies to what? 9 * (the square root of 2) 3 * (the square root of 2) 2 * (the square root of 3) 6 * (the square root of 3) Reveal answer Fill a bubble to check yourself B Correct answer Explanation √18 = √(9 × 2) = √9 × √2 = 3√2. This simplification uses the property √(ab) = √a × √b. We look for the largest perfect square factor of 18, which is 9, leaving 2 inside the radical. The answer is 3√2, not 2√3, 6√3, or 9√2.