Know that numbers that are not rational are called irrational

What you'll learn

1. Define rational and irrational numbers and classify given numbers correctly into one category or the other
2. Explain informally that every real number has a decimal expansion, and that a rational number's decimal expansion either terminates or eventually repeats
3. Show, using examples and informal reasoning, why long division of any fraction p/q must eventually produce a repeating decimal
4. Convert a repeating decimal to its equivalent fraction form using the algebraic subtraction technique
5. Recognize that irrational numbers -- such as sqrt2 and pi -- have decimal expansions that neither terminate nor repeat, and that they cannot be expressed as a ratio of two integers