Based on the relationship between each polygon and the number inside it, the…

The number inside each polygon equals the factorial of its number of sides. A triangle has 3 sides and holds \(3! = 6\); a square has 4 sides and holds \(4! = 24\); a pentagon has 5 sides and holds \(5! = 120\). A hexagon has 6 sides, so \(X = 6! = 720\).