Transcript ESTIMATING PRODUCTS - Ed2Net Learning, Inc.

CHAPTER 7
ESTIMATING PRODUCTS
AND
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MULTIPLYING FRACTIONS AND
WHOLE NUMBERS
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CHAPTER 7
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ESTIMATING PRODUCTS
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CHAPTER 7
Objectives
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• Estimating product using compatible
numbers and rounding.
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CHAPTER 7
Prerequisite Skill
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1010
1011
1. Find
the1101
GCF 0001
of the0100
following:
a) 12, 18
GCF = 6
b) 20, 40
GCF = 20
c) 13, 23
GCF = 1
2. Convert the improper fraction to mixed numbers:
a) 55/22
=
2½
b) 38/4
=
9½
c) 12/5
=
2 2/5
3. Round each fraction to 0, ½ or 1:
a) 1/10
=
0
b) 4/7
=
½
c) 13/14
=
1
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CHAPTER 7
Estimating Products
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• One way to estimate product is to use
compatible numbers , which are numbers
that are easy to divide mentally.
• Another method is estimating numbers by
rounding to 0, ½ or 1.
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CHAPTER 7
Estimate using Compatible Numbers
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• Estimate ¼ x 21.
¼ x 21 means ¼ of 21
Find a number close to 21 that is a multiple of 4
20 and 4 are compatible
¼ x 21
¼ x 20
numbers since 20 ÷ 4 = 5
¼ x 20 = 5
20 ÷ 4 = 5
So, ¼ x 21 is about 5
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CHAPTER 7
Example – 2
•
•
•
•
•
•
Estimate 2/3 x 97
Estimate 1/3 x 97
1/3 x 97
1/3 x 96 96 and 3 are compatible numbers
1/3 x 96 = 32
96 ÷ 3 = 32
If 1/3 of 96 is 32, then 2/3 of 96 = 2 x 32 =64
So, 2/3 of 97 is about 64
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CHAPTER 7
Try to do by yourself
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Estimate each product:
• 3/5 x 27
=
3/5 x 25 = 15
• 5/8 x 39
=
5/8 x 40 = 25
• 4/7 x 30
=
4/7 x 28 = 16
• 5/9 x 20
=
5/9 x 18 = 10
• ¼ x 33
=
¼ x 36 = 9
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CHAPTER 7
Estimate by rounding to 0, ½ or 1
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Estimate 1/3 x 8/9
• 1/3 x 8/9 = ½ x 1 = 1
• 1/10 x 6/14 = 0 x ½ = 0
• 9/16 x 27/50 = ½ x ½ = 1
• 24/26 x 29/31 = 1 x 1 = 1
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CHAPTER 7
Now Your Turn
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Estimate each product:
a) 4/5 x 2/9
=
1x0=0
b) 5/8 x 11/12 =
1x1=1
c) ¼ x 9/10
=
0 x1 =1
d) 5/11 x 1/9 =
½x0=0
e) 9/10 x ¾
=
1x1=1
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CHAPTER 7
Let’s have fun
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• Free Kids Games from theKidzpage.com -Breakdown Flash Game
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CHAPTER 7
Estimate with Mixed Numbers
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• Round each mixed number to the nearest
whole number
• For example: 11 ¾ x 8 1/7
• 11 ¾ to 12 and 8 1/7 to 8
• 11 ¾ x 8 1/7 = 12 x 8 = 96
• So, the product is about 96
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CHAPTER 7
Your Turn!
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•
•
•
•
Estimate each product:
7 2/3 x 5 1/6 =
8 x 5 = 40
2 9/10 x 11 ¾ =
3 x 12 = 36
8 ¼ x 8 6/7 =
8 x 9 = 72
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CHAPTER 7
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MULTIPLYING FRACTIONS
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CHAPTER 7
Multiply Fractions and Whole
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1011
• To multiply fraction and a whole number,
first write the whole number as a fraction.
Then multiply the numerator and
denominator. Simplify the fraction.
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CHAPTER 7
Multiplying fractions & whole numbers
• Example 1: ¼ x 13 = ¼ x 13/1
= 1 x 13
4x1
= 13/4 = 3¼
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CHAPTER 7
Example – 2
• ¾ x 24 = ¾ x 24/1
= 3 x 24
4x1
= 72/4 = 18
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CHAPTER 7
Your Turn
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Multiply and Simplify:
1. 1/8 x 15
=
7 1/8
2. 1/7 x 28
=
4
3. 3/8 x 2
=
¾
4. 4/6 x 12
=
8
5. 1/6 x 37
=
6 1/6
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CHAPTER 7
Let’s solve this puzzle
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• http://www.thekidzpage.com/onlinejigsawp
uzzles/jigsaw-puzzles/12-piecejigsaw/012206hermitcrab.html
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CHAPTER 7
Word Problems
• Funky and his froggie friends took 39
minutes to reach Frog School. If they
hopped for 2/3 of the time, how many
minutes did they spend for hopping?
• 2/3 x 39 =
2/3 x 39/1 = 2 x 39 = 78
3x1
3
= 26
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CHAPTER 7
Now your turn
• In my class of 48 students, 1/8 study French and
1/6 study Russian and 5/12 of them study English
as their language subject. How many students
study French, English and Russian?
• Number of students studying French = 1/8 x 48
=6
Number of students studying English = 5/12 x 48
= 5 x 4 = 20
Number of students studying Russian = 1/6 x 48
=8
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CHAPTER 7
Assessment Sheet- 1
Estimate:
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1.
6/11 x 78
=
2.
7/13 x 24
=
3.
5/9 x 71
=
4.
10 2/3 x 1 ¼
=
5.
2 ¾ x 7 2/3
=
6.
1 3/5 x 1 ¾
=
Estimate by rounding numbers
•
5/8 x ¾
=
8.
4/5 x 1/10
=
9.
3/5 x 2
=
10. 3/7 x ¾
=
42
14
40
11 x 1
= 11
3x8
= 24
2x2=4
½x1=½
1x0=0
½ x 2 =1
½x1=½
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CHAPTER 7
Assessment Sheet – 2
Multiply
0011 0010
1010 and
1101simplify:
0001 0100 1011
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
3/8 x 3 =
4/15 x 20 =
5/4 x 8 =
4/7 x 21 =
9/10 x 23=
4/5 x 50 =
3/5 x 2 =
6/15 x 45 =
½ x 15 =
9/81 x 36 =
1 1/8
5 1/3
10
12
2 7/10
40
1 1/5
18
7½
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CHAPTER 7
Good Work
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Do the problems carefully
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