Math 221 Section 1.1

Yvette Gonzalez-Smith

Ashford University

Classification of numbers

There are a few classifications of numbers. They include • Natural Numbers• Whole Numbers• Rational Numbers• Irrational Numbers• Real Numbers

Natural and Whole Numbers

• Natural numbers are counting numbers that do not include zero. Example 1, 2, 3 . . .

• Whole Numbers are natural numbers including zero

Rational Numbers

• Numbers that can be written as a fraction where top number on the fraction can be zero but the bottom number on the fraction can not be zero.

Examples:

Example of what a rational number cannot be

Irrational Numbers

Irrational Numbers are what rational numbers are not. This includes decimals that repeat forever.

Examples

Real Numbers

• Real numbers are numbers that have a place on the number line.

Examples

Number Lines

How to draw a number line:

1. Draw a horizontal line

2. Draw vertical lines that are evenly spaced

3. Add numbers with zero in the center

0 1 2 3-1-2-3

Absolute Value

Absolute Value is the how far a number is from zero

Both 3 and -3 are 3 spaces from zero so absolute value is 3 so |-3| =3 and |3|=3

0 1 32-1-2-3

Interval Notation

(Dugopolski 2012)

Interval Notation

(2,10) means every number between 2 and 10

[-3, 5] means every number between -3 and 5 including -3 and 5

[-5, 7) means every number greater than and equal to -5 and every number less than 7

(2, 13] means every number greater than 2 and less than and equal to 13

Opposite of an opposite

The opposite of -4 is 4 and the opposite of 4 is -4

-(-4) = 4

-(4) = 4

Works Cited

Dugopolski, M (2012) Elementary and Intermediate Algebra. New York, NY: Mc-Graw Hill

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