This document discusses square roots and irrational numbers. It defines a square root as the opposite of a square, and provides examples of simplifying square roots. It also discusses estimating square roots when they are not perfect squares, and classifying numbers as rational or irrational. Some key points are: - The square root of a number is the opposite of squaring it. Square roots are indicated with the radical symbol. - Perfect squares are integers that when squared result in another integer, like 4, 9, 16. - Square roots that do not result in a perfect square can be estimated by looking at the closest perfect squares. - Real numbers are either rational (can be expressed as a ratio of