Numbers Free powerpoints at http://www.worldofteaching.com Perfect Square •Squares of whole numbers Square root • One of two equal factors of a number. If a squared equals b then a is the square root of b. The square root of 144 is 12 because 12 squared is 144. Radical Sign •The sign used to represent a nonnegative square root. Principle Square Root •A nonnegative square root Irrational Number •Numbers that cannot be expressed as a/b. Real Number •Irrational numbers together with rational numbers to form the set of all numbers. Natural Numbers •1, 2, 3, 4... Whole Numbers •0, 1, 2, 3, 4, 5... Integers • The whole numbers and their opposites. • ...-3, -2, -1, 0, 1, 2, 3... Rational Numbers • Any number that can be expressed in the form a/b where a and b are integers and b is not equal to 0.