1. 2.1 and 2.2: RATIONAL NUMBERS

2. Express rational numbers as decimals and decimals as fractions.
terminating decimal
repeating decimal
bar notation
Main Idea/Vocabulary

3. KC 1

4. 2-1/2-2 notes

5. Write a Fraction as a Decimal
Write as a decimal. .1 8 7 5
Divide 3 by 16.
–16 14
–128 12
–112 8
–80
Answer:
Example 1

6. A B C
D. 0.16 A B C D
Example 1

7. Write a Repeating Decimal
You can divide as shown in Example 1 or use a calculator.
– –
ENTER ÷
Answer:
Example 2

8. A. 5.1
B. 5.15
C. 5.2
D. 5.9 A B C D
Example 2

9. Round a Repeating Decimal
AGRICULTURE A farmer lost the fruit on 8 of 15 orange trees because of unexpected freezing temperatures. Find the fraction of the orange trees that did not produce fruit. Express your answer as a decimal rounded to the nearest thousandth.
To find the fraction of trees that did not produce fruit, divide the number of lost trees, 8, by the total number of trees, 15.
ENTER ÷
Look at the digit to the right of the thousandths place. Round down since 3 < 5.
Example 3

10. Round a Repeating Decimal
Answer: The fraction of fruit trees that did not produce fruit was
Example 3

11. SCHOOL In Mrs. Townley’s eighth grade science class, 4 out of 22 students did not turn in their homework. Find the fraction of the students who did not turn in their homework. Express your answer as a decimal rounded to the nearest thousandth. A B C D A B C D
Example 3

12. Write a Decimal as a Fraction
Write 0.32 as a fraction.
0.32 is 32 hundredths.
Simplify.
Answer:
Example 4

13. Write 0.16 as a fraction. A. B. C. D. A B C D
Example 4

14. Write a Decimal as a Fraction
ALGEBRA Write 2.7 as a mixed number.
Let N = 2.7 or Then 10N =
Multiply N by 10 because 1 digit repeats.
Subtract N = to eliminate the repeating part,
Example 5

15. Write a Decimal as a Fraction
10N = –1N =
9N = N – 1N = 9N
Divide each side by 9.
Simplify.
Answer:
Example 5

16. ALGEBRA Write 1.7 as a mixed number.C. D. A B C D
Example 5

17. End of the Lesson
End of the Lesson

18. Compare and order rational numbers.
Main Idea/Vocabulary

19. 2-1 & 2-2 Pg #3-57 e.3 Pg #3-45 e.3
2-1/2-2 notes

20. 2-1/2-2 notes

21. Compare Positive Rational Numbers
Replace ■ with <, >, or = to make ■ a true sentence.
Write as fractions with the same denominator.
Answer:
Example 1

22. Replace ■ with <, >, or = to make ■ a true sentence.
B. <
C. = A B C
Example 1

23. Compare Using Decimals
Replace ■ with <, >, or = to make 0.7 ■ a true sentence. ■ ■
Express as a decimal.
In the tenths place, 7 > 6.
Answer:
Example 2

24. Replace ■ with <, >, or = to make ■ 0.5 a true sentence.
B. <
C. = A B C
Example 2

25. Order Rational Numbers
CHEMISTRY The values for the approximate densities of various substances are shown in the table. Order the densities from least to greatest.
Write each fraction as a decimal.
Example 3

26. Order Rational Numbers
Answer: From the least to the greatest, the densities are
So, the nylon is the least dense, and aluminum is the most dense.
Example 3

27. AMUSEMENT PARKS The ride times for five amusement park attractions are shown in the table. Order the lengths from least to greatest. A. B. C. D. A B C D
Example 3

28. Compare Negative Rational Numbers
Replace ■ with <, >, or = to make –4.62 ■ –4.7 a true sentence.
Graph the decimals on a number line.
Answer: Since –4.62 is to the right of –4.7, –4.62 > –4.7.
Example 4

29. Replace ■ with <, >, or = to make –2.67 ■ –2.7 a true sentence.
B. >
C. = A B C
Example 4

30. Compare Negative Rational Numbers
Replace ■ with <, >, or = to make a true sentence.
Since the denominators are the same, compare the numerators.
Answer:
Example 5

31. Replace ■ with <, >, or = to make a true sentence.
B. <
C. = A B C
Example 5

32. End of the Lesson
End of the Lesson