Chapter 5 Lesson 2 Rational Numbers Pgs. 205-209

What you will learn (maybe): Write rational numbers as fractions Identify and Classify rational numbers

Vocabulary:



Rational Number (205): A number that can be written as a fraction. Terminating decimals are rational numbers because they can be written as a fraction with a denominator of 10, 100, 1000 and so on…..

Ex.) 0.75 = 3/4 28 = 28/1 1 1/4 = 5/4 _ -0.3 = - 1/3

Write Mixed Numbers and Integers as Fractions

Write 5 2/3 as a fraction.

2 17

5

Turn the Mixed # into an improper fraction Write -3 as a fraction -3 = -3 1

or -

3 1

Write Terminating Decimals as Fractions

Write each decimal as a fraction or mixed number in simplest form.

0.48 = 48 100 Simplify: 12 25 See the digit chart on pg. 206

6.375 = 6 375 1000 Simplify: 6 3 8

Write Repeating Decimals as Fractions _

Write 0.8 as a fraction in simplest form Let N represent the number: N= 0.888…..

Multiply each side by 10 since one digit repeats: 10 N = 10 (.888…) 10N = 8.888…..

Subtract N from 10N to eleminate the repeating part. 0.888….

10N = 8.888… - (N = 0.888…) 9N = 8 9N = 8 9 9 N = 8 9

Big Idea! Noteworthy!!

All rational numbers can be written as terminating or repeating decimals .

Decimals that do not terminate or repeat are called irrational numbers because they CANNOT be written as fractions Examples of irrational numbers: Pi = 3.141592654….. ----> digits DO NOT repeat 4.232232223…….---->same blocks of digits DON’T repeat

Refer to the Concept Summary on Pg. 207

Identify all sets to which each number belongs: -6

Integer, Rational

2 4/5

Rational

0.914114111…

Irrational

You Try!

Write each number as a fraction.

-2 1/3 10 7 2/3

- 7/3 10 1 23 3

Write each number as a fraction or mixed number in simplest form.

.8

4/5

6.35

6 7/20 _

-0.7

_ 7 9