Key Standards MC C8.NS.1 Know that numbers that are not rational are called irrational. Understand informally that every number has a decimal expansion; for rational numbers show that the decimal expansion repeats eventually, and convert a decimal expansion which repeats eventually into a rational number. MCC8.NS.2 Use rational approximations of irrational numbers to compare the size of irrational numbers, locate them approximately on a number line diagram, and estimate the value of expressions (e.g., π2). For example, by truncating the decimal expansion of √2 (square root of 2), show that √2 is between 1 and 2, then between 1.4 and 1.5, and explain how to continue on to get better approximations.

Number system Real numbers: This group is made up of all the Rational and Irrational Numbers. Rational numbers: This is any number that can be expressed as a ratio of two integers. As decimals they terminate or repeat. Irrational numbers: This is any number that can not be expressed as an integer divided by an integer. These numbers have decimals that never terminate and never repeat with a pattern.

Rational Numbers: A rational number is a number that can be written as a ratio. That means it can be written as a fraction, in which both the numerator (the number on top) and the denominator (the number on the bottom) are integers. Every whole number is a rational number, because any whole number can be written as a fraction. For example, 4 can be written as 4/1, 65 can be written as 65/1, and 3,867 can be written as 3,867/1.

Irrational Numbers: All numbers that are not rational are considered irrational. An irrational number can be written as a decimal, but not as a fraction with integers.

Play the game. Which of the following are Rational numbers?

Rational vs. Irrational Quiz Label the following numbers as either rational or irrational. 1.) pi 2.) ) ) ) ) ) √2 8.) √25