### Have you wonder what is the difference between a rational number and an irrational one? What is the difference between a whole number and a natural one? In this lesson you may learn to differentiate all the sets of real numbers. Learn the properties of real numbers and apply them to simplify algebraic expressions. Optionally, if you wish you will be able to write on the screen, or highlight important parts on it using the MARKER TOOLS menu available on the upper right top of the screen. You have some useful definitions when you scroll down the screen.

** Lesson's Content **

** Lesson's Glossary **

**Real number: Any number which can be negative, positive, or zero.**

**Additive inverses: The opposite of a number.**

**Identity element for addition: Zero (0). **

Identity element for multiplication: One (1).

**Integers: All numbers in the set containing positive integers, negative integers, and zero.**

** Irrational numbers: Any number that is impossible to write it as a fraction. A decimal number that doesnâ€™t end or keeps repeating.**

**Negative integers: The numbers -1,-2,-3,-4, and so on.**

**Negative number: The opposite of a positive number.**

Negative side: The side situated at the left of the origin in a horizontal number line.

**Positive integers: Natural numbers: 1, 2, 3, 4, 5, ...**

Positive number: The opposite of a negative number.

Positive side: The side situated to the right of the origin in a horizontal number line.

**Real number: Any number which can be negative, positive, or zero.**

Reciprocals: Any two numbers which multiplied give 1; also known as multiplicative inverse.

**Whole numbers: All numbers in the set containing zero and all positive integers.**

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