Download Review 2 Multiplying Rational Numbers Review

Rational Numbers: Multiplying Rational Numbers Review
CCSS Standard
Prerequisite for 8.NS.1
Materials: In-class worksheet: Multiplying Decimals, Fractions, and Mixed
Numbers Homework worksheet: Multiplying Fraction/Decimal
Review
Suggested Lesson Structure:
 Hand out worksheets
 Allow students to work independently on the worksheet for 10-15 minutes.
 Then, have students work in groups to discuss the worksheet and
compare answers for another 10-15 minutes.
 Finally, go over the answers and discuss problems where students
encountered difficulties.
Homework: Multiplying Fractions/Decimals Review Worksheet
(Students will use the In-class worksheet as a guide - it is recommended
to have
students keep the In-class worksheets in the notes section of
their binder)
Reference Materials:
Holt McDougal Mathematics Grade 8: Ch 1-2: Holt McDougal
Mathematics Explorations in CORE MATH Grade 8 ISBN 978-0-54764727-2
EXPLORATIONS 7: Holt McDougal Mathematics Explorations in CORE
MATH Grade 7 ISBN 978-0-547-87653-5 (Student and Teacher Addition)
Videos/Interactives:
Student Videos:
Multiply decimals 7:25 minutes
http://www1.teachertube.com/viewVideo.php?video_id=5823
Multiply mixed numbers 2:25 minutes
http://www1.teachertube.com/viewVideo.php?video_id=10270
Rational Numbers
Multiplying Decimals, Fractions, Mixed Numbers
Multiplying Decimals
You bought and IPAD for $450.50. After a year, its value depreciated to 0.82 of its original value. What
was the value of the IPAD after one year?
Step 1: Multiply as you would with whole numbers.
4 5 0 5 0
𝑥
0 8 2
9 0 1 0 0
______________0
multiplication
= ___________
Remember you must place a zero as a place holder and then start your
by 8. (multiplying by 80)
Step 2: Count the number of decimal places in each factor. Mark off the same number of decimal
places in the product.
4 5 0. 5 0
𝑥
_0 . 8 2
___________
_____ decimal places?
_____ decimal places?
end of
_____ + _____ = decimal places? ______
After one year, the IPAD had a value of ________________?
Count in four places from the
the number and place your
decimal.
REFLECT
1a.
You can use estimation to check that your answer is reasonable. Round $29,906 to its greatest
place value.
$450.50 ≈ _________________
0.8 𝑡𝑖𝑚𝑒𝑠 ___________ = ________________
Is the answer reasonable? Compare your answer above to your answer above in Step 2 and
explain.
1b.
Why is rounding to the greatest place value an effective strategy for check the solution to the
car’s value problem?
Reflection:
1c.
Anya’s $25,000 dollar salary was multiplied by a factor of 1.2 because she received a 20%
increase with her new position. What is her new salary?
Multiplying Fractions
1
2
The evening temperature is decreasing at a rate of 1 °𝐹 per hour. What will the change in temperature
1
be in 4 2 hours, to the nearest whole degree?
1
2
1
2
Multiply the rational number −1 𝑎𝑛𝑑 4 .
Step 1: Rename any mixed numbers as fractions greater than one.
−1
1
−1
1
2
×4
1
×4
1
2
=
×
=?
Step 2: Multiply numerator by numerator and denominator by denomiator. Simplify, if possible, and
round the answer to the nearest whole degree.
2
______?
1
2
2
= −
= −6
After 4 hours, the temperature change will be about _________°𝐹.
Rounded
PRACTICE:
3
1. (8) � �
4
___________
3. � � �1 �
4
8
3
___________
5. (0.02)(4.6)
___________
___________
8
�18� �15�
4.
(2)(5.2)
___________
3
5
2.
Multiplying Fractions/Decimals
Name:
______________________________
1. Between which letters on the number line is 0.23?
___________________
C D E F G H I
-5 -4 -3 -2 -1
2. Find the product of
2
2
3
.
0
1
2
3
4
5
1
3
___________________
2
2.038
3. Find the product of
___________________
X 1.4
4. Find the product of 2,947 and identify the digit in the thousands place.
X 316
___________________
5. Given 3! =3 ∙ 2 ∙ 1, simplify
6!
4!2!
___________________
6. Evaluate:
5!
2!
___________________
7. Find the value of the expression: 3𝑥
___________________
− 𝑦, when 𝑥 = 2 𝑎𝑛𝑑 𝑦 = 5.
8. Find the value of the expression: 12𝑥𝑦 − 1, when 𝑥
___________________
=
2
3
𝑎𝑛𝑑 𝑦 =
1
3