Fractions, Decimals, and Percents

1. Fractions, Decimals, and Percents Lesson Objective: Students will understand why fractions, decimals, and percents are useful in “real life”; why we might want to change fractions into decimals.

2. 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

3. Vocabulary: • Terminating decimal. • Repeating decimal. • What is a numerator? • What is a denominator? • What is a quotient?

4. Numbers can be written in both fraction and decimal form

5. A fraction represents division • Means?

6. 1 divided by 10

7. Use your calculator and divide 1 by 10 • What is the answer? • Did you need to use your calculator?

8. 0.1!

9. Use your calculator, write each fraction as a decimal

10. What patterns do you see in your answers?

11. 0.090909091 • 0.181818182 • 0.272727273 • 0.363636364

12. What patterns did you see? • The repeating digits are multiples of nine. 0.090909091 0.181818182 0.272727273 0.363636364 • The numerator multiplied by 9 gives the repeating digits. 1x9=9; 2x9=18; 3x9=27; 4x9=36 • The repeating digits follow the decimal points.

13. Use a calculator, write each fraction as a decimal…

14. Repeating Decimals • 0.111111111 • 0.222222222 • 0.333333333

15. Predict the fraction form of these decimals… • 0.777 777 777… • 0.888 888 888…

16. What do you notice about the last digit in the calculator display?

17. 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

18. Try to Write each fraction with denominator 10, 100, or 1000 13/200 13/200 x 5 Remember to multiply the numerator and denominator by 5.

19. = 65/100 or .65