Fractions, Decimals, and Percents

FRACTIONS, DECIMALS, AND PERCENTSLesson Objective: Students will understand why fractions, decimals, and percents are useful in “real life”; why we might want to change fractions into decimals.

REMEMBER… We use fractions and decimals when we

shop, measure, in sports, recipes, and business, and when we work with percents.

We use percents when we shop, to find sale prices, to calculate taxes, and to get girlfriends

VOCABULARY: Terminating decimal.

Repeating decimal.

What is a numerator?

What is a denominator?

What is a quotient?

NUMBERS CAN BE WRITTEN IN BOTH FRACTION AND DECIMAL FORM

A FRACTION REPRESENTS DIVISION Means?

1 DIVIDED BY 10

USE YOUR CALCULATOR AND DIVIDE 1 BY 10 What is the answer? Did you need to use your calculator?

0.1!

USE YOUR CALCULATOR, WRITE EACH FRACTION AS A DECIMAL

WHAT PATTERNS DO YOU SEE IN YOUR ANSWERS?

0.090909091

0.181818182

0.272727273

0.363636364

WHAT PATTERNS DID YOU SEE? The repeating digits are multiples of nine.0.0909090910.1818181820.2727272730.363636364

The numerator multiplied by 9 gives the repeating digits.

1x9=9; 2x9=18; 3x9=27; 4x9=36 The repeating digits follow the decimal

points.

USE A CALCULATOR, WRITE EACH FRACTION AS A DECIMAL…

REPEATING DECIMALS 0.111111111

0.222222222

0.333333333

PREDICT THE FRACTION FORM OF THESE DECIMALS… 0.777 777 777… 0.888 888 888…

WHAT DO YOU NOTICE ABOUT THE LAST DIGIT IN THE CALCULATOR DISPLAY?

IN THE FRACTIONS WHICH HAD 9 AS A DENOMINATOR: When the repeating digit was greater than 4,

the calculator rounded the last digit up to the next number.

For example: 5/9 = 0.555 555 556

TRY TO WRITE EACH FRACTION WITH DENOMINATOR 10, 100, OR 100013/200

13/200 x 5

Remember to multiply the numerator and denominator by 5.

= 65/100 or .65