Anxiety Disorder Statistics. Anxiety Disorders affect 18.1 percent of adults in the United States (approximately 40 million adults between the ages of 18 to 54).
Perfect square. Perfect square is an element of algebraic structure which is equal to the square of another element. Square number, a perfect square integer.
Perfect competition is a market structure where many firms offer a homogeneous product. Because there is freedom of entry and exit and perfect information, firms will make normal profits and prices will be kept low by competitive pressures.