Download 2 GCF Notes 8C3.notebook

2 GCF Notes 8C3.notebook
August 18, 2016
review day 2 divisibility, factors, gcf Jun 28­9:43 PM
Objective: To correctly apply divisibility rules in order to find factors. To be able to find the Greatest Common Factor
Virtue/Skill: This is necessary for when we simplify number and variable fractions but also is a key component of factoring polynomial expressions for Algebra
Jul 16­10:06 AM
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2 GCF Notes 8C3.notebook
August 18, 2016
Aug 14­12:15 PM
Divisibility
by 2: If the number is even (ends in 0,2,4,6, or 8)
by 3: If the sum of the digits is divisible by 3 Rules
(ex. 2058, 2 + 0 + 5 +8 =15 and 3 goes into 15, so it goes into 2058)
by 4: If the number formed by the last two digits are a multiple of 4 (ex. 196, 4 goes into 96 so it goes into 196)
by 5: If the last number ends in a 0 or 5 by 6: If 2 and 3 are factors, then 6 is
by 8: If the number formed by the last three digits are a multiple of 8
by 9: If the sum of the digits is divisible by 9
(ex. 837, 8+3+7=18 and 9 goes into 18, so it goes into 837)
by 10: If the last number is a 0
ex.1 List the factors of 240 ex.2 List the factors of 216
Aug 12­12:49 PM
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2 GCF Notes 8C3.notebook
Factors
August 18, 2016
Factors: numbers that when multiplied together make a new number
ex. Factors of 36
GCF
Greatest Common Factor: the factor that is shared that is the biggest number.
ex. GCF (32, 48)
Aug 12­12:49 PM
Cake
Method
A fast and easy way to find the GCF of any amount numbers.
ex. GCF (32, 48)
Why it works: We are looking for common factors, when we factor out a number the rest of the factors are left and we can keep looking and factoring out more common ones. Since factors are numbers that when multiplied together make a new number, the shared factors that are taken out only need to be multiplied together to find the greatest common factor. ex.2 GCF (36, 108)
Aug 12­12:49 PM
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2 GCF Notes 8C3.notebook
ex. 3
August 18, 2016
GCF (42, 84, 98) ex. 4 GCF (78, 117, 156) Aug 13­12:21 PM
http://illuminations.nctm.org/Activity.aspx?id=4134
Aug 13­11:33 AM
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2 GCF Notes 8C3.notebook
August 18, 2016
Summary
Objective: To correctly apply divisibility rules in order to find factors. To be able to find the Greatest Common Factor
Virtue/Skill: This is necessary for when we simplify number and variable fractions but also is a key component of factoring polynomial expressions for Algebra
Assignment: Workbooks pg. 4,7 all (on page 7 there will be a
third number and you will use the cake method)
or
Challenge: pg. 4, 7 all (but pg. 7 will have four numbers)
Please add to your homework pg. 7: 1. 90
2. 24
3. 75
7. 140
8. 108
9. 192, 216
13. 384, 768 14. 465, 435
4. 154
5. 68
10. 220, 748
6. 70
11. 208, 364 12. 612, 816
15. 1720, 1680 Jul 16­10:06 AM
Exit Questions
1. What did you think about using Prodigy today?
2. Find the GCF for : 48, 128, and 224
Jul 16­10:05 AM
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2 GCF Notes 8C3.notebook
August 18, 2016
Answers to Homework on pg. 4
1. 2,3,6,9
2. 2,4,5 10 3. 2,4 4. 2,3,4,6
5. 5 7. 2,3,6
11. 5
6. none of these
8. 3,5
12. 3
9. 2
13. 2,4
10. 2,4,5,10
14. 2,5,10
15. 3
Answers to Homework on pg. 4 and 7
1. 6
2. 2
3. 5
4. 22
5. 4
7. 15
8. 18
9. 24
10. 44
12. 68
13. 128
14. 15
15. 40
6. 7
11. 26
Aug 18­3:40 PM
Aug 18­3:45 PM
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Attachments
http://illuminations.nctm.org/Activity.aspx?id=4134