1. copyright©amberpasillas2010
Add and Subtract
Fractions
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2. 3 4 Parts of a Fraction = the number of parts
Add and Subtract Fractions
Parts of a Fraction 3
= the number of parts 4
= the total number of parts that equal a whole
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3. 3 4 Parts of a Fraction = numerator = denominator
Add and Subtract Fractions
Parts of a Fraction 3
= numerator 4
= denominator
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4. Add and Subtract Fractions
A Common Multiple is a number that is a multiple of two or more numbers.
Some multiples of 3 & 6
6, 12, 18, 24, 30, 36, 42
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5. Add and Subtract Fractions
The LCM is the smallest multiple that two numbers have in common.
5 = 5, 10, 15, 20, 25, 30
6 = 6, 12, 18, 24, 30, 36
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6. To Add or Subtract Fractions With Unlike Denominators
Add and Subtract Fractions
To Add or Subtract Fractions With Unlike Denominators
List the multiples of each denominator to find the LCM. 1 5
= 5, 10, 15, 20, 25, 30 1 + 10
= 10, 20, 30, 40, 50
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7. To Add or Subtract Fractions With Unlike Denominators
Add and Subtract Fractions
To Add or Subtract Fractions With Unlike Denominators
Compare your lists. Which multiples do 5 and 10 have in common? 1 5
= 5, 10, 15, 20, 25, 30 1 + 10
= 10, 20, 30, 40, 50
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8. To Add or Subtract Fractions With Unlike Denominators
Add and Subtract Fractions
To Add or Subtract Fractions With Unlike Denominators
Use the lowest common multiple as the denominator. 1 5
= 5, 10, 15, 20, 25, 30 1 + 10
= 10, 20, 30, 40, 50
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9. To Add or Subtract Fractions With Unlike Denominators
Add and Subtract Fractions
To Add or Subtract Fractions With Unlike Denominators
This number is also called the least common denominator. 1 5
= 5, 10, 15, 20, 25, 30 1 + 10
= 10, 20, 30, 40, 50
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10. Add and Subtract Fractions
SHORTCUT: Check to see if the smaller denominator divides evenly into the larger denominator. If it does, use the larger denominator for your LCD or LCM. 1
5 will divide evenly into 10,
so 10 is your denominator. 5 1 + 10
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11. 1 5 10 1 + 10 10 Add and Subtract Fractions
Rewrite the fractions using the least common denominator or least common multiple. 1 5 10 1 + 10 10
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12. Add and Subtract Fractions
Find the equivalent fractions for 1/5 & 1/10 with 10 as the denominator.
You know that 1/10
is equal to 1/10 so
Put a 1 over the
Denominator of 10. 1 5 10 1 1 + 10 10
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13. Add and Subtract Fractions
Find the equivalent fractions for 1/5 & 1/10 with 10 as the denominator.
To find the top
number, ask yourself
what do you multiply
the 5 by to get 10. 1 5 10 1 1 + 10 10
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14. Add and Subtract Fractions
Find the equivalent fractions for 1/5 & 1/10 with 10 as the denominator. 2
Since you are looking for the equivalent fraction you know the numerator must also be multiplied by 2. 1
x 2 = 5 10
x 2 1 1 + 10 10
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15. 2 1 5 10 1 1 + 10 10 Now just add the numerators. x 2 = x 2
Add and Subtract Fractions
Now just add the numerators.
Remember when
adding fractions you never add the denominators. 2 1
x 2 = 5 10
x 2 1 1 + 10 10 3 10
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16. Add and Subtract Fractions
Identity Property states that any number multiplied by one equals itself
This is useful to know so you can find a common denominator for adding and subtracting fractions.

17. 1 2 8 1 + 8 8 Use the short cut to find the Least Common Denominator
Add and Subtract Fractions
Use the short
cut to find the
Least Common
Denominator
(LCD). 1 2 8 1 + 8 8
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18. 1 2 8 1 + 8 8 x 4 = x 1 = Now find the equivalent fractions for
Add and Subtract Fractions
Now find the
equivalent
fractions for
1/2 & 1/8. 1 2 8
x 4 = 1 + 8
x 1 = 8
Ask what do you multiply 2 by to get 8
and what do you multiply 8 by to get 8.
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19. 1 4 2 8 1 + 8 8 x 4 = x 4 = x 1 = Since you are writing equivalent
Add and Subtract Fractions
Since you are
writing equivalent
fractions, now
multiply the
numerator by the
same number you
did on the
denominator. 1 4
x 4 = 2 8
x 4 = 1 + 8
x 1 = 8
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20. 1 4 2 8 1 1 + 8 8 x 4 = x 4 = x 1 = x 1 = Since you are
Add and Subtract Fractions
Since you are
writing equivalent
fractions, now
multiply the
numerator by the
same number you
did on the
denominator. 1 4
x 4 = 2 8
x 4 = 1 1
x 1 = + 8
x 1 = 8
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21. 1 4 2 8 1 1 + 8 8 5 8 x 4 = x 4 = x 1 = x 1 = Now add numerators.
Add and Subtract Fractions
Now add
numerators.
The denominator
stays the same. 1 4
x 4 = 2 8
x 4 = 1 1
x 1 = + 8
x 1 = 8 5 8
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22. 2 5 15 1 + 3 15 Find the least least common multiple for 5
Add and Subtract Fractions
Find the least
least common
multiple for 5
and 3. Write it as
your denominator 2 5 15 1 + 3 15
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23. 2 5 15 1 + 3 15 x 3 = x 5 = Ask yourself what do you multiply the
Add and Subtract Fractions
Ask yourself
what do you
multiply the
denominator
by to get 15. 2 5 15
x 3 = 1 + 3
x 5 = 15
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24. 2 6 5 15 1 + 3 15 x 3 = x 3 = x 5 = Multiply the numerator by the same
Add and Subtract Fractions
Multiply the
numerator
by the same
number you
did in the
denominator 2 6
x 3 = 5 15
x 3 = 1 + 3
x 5 = 15
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25. 2 6 5 15 1 5 + 3 15 x 3 = x 3 = x 5 = x 5 = Multiply the numerator
Add and Subtract Fractions
Multiply the
numerator
by the same
number you
did in the
denominator. 2 6
x 3 = 5 15
x 3 = 1 5
x 5 = + 3
x 5 = 15
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26. Add and Subtract Fractions
Add your
numerators. The
denominator
stays the
same. 2 6
x 3 = 5 15
x 3 = 1 5
x 5 = + 3
x 5 = 15 11 15
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27. Add and Subtract Fractions1 2
x 2 = 6 12
x 2 = 1 3
x 3 = + 4
x 3 = 12 5 12
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28. ALWAYS SIMPLIFY YOUR ANSWER IF YOUR ANSWER IS AN IMPROPER FRACTION!
Add and Subtract Fractions
ALWAYS SIMPLIFY YOUR ANSWER IF YOUR ANSWER IS AN IMPROPER FRACTION! 4 12
x 3 = 5 15
x 3 = 2 10
x 5 = + 3
x 5 = 15 22 15
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29. 1 7 15 22 15) 22 15 15 7 Add and Subtract Fractions
ALWAYS SIMPLIFY YOUR ANSWER IF YOUR ANSWER IS AN IMPROPER FRACTION!
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30. Add and Subtract Fractions5 20
x 4 = 6 24
x 4 = 1 3
x 3 = - 8
x 3 = 24 17 24
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31. Add and Subtract Fractions2 6
x 3 = 3 9
x 3 = 1 1
x 1 = - 9
x 1 = 9 5 9
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32. Add and Subtract Fractions4 2
x 2 = 4 8
x 2 = 2 2
x 1 = + 8
x 1 = 8 6 3 = 8 4
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33. Add and Subtract Fractions12 4
x 3 = 15 5
x 3 = 10 2
x 5 = - 15 3
x 5 = 2 15
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34. REMEMBER: To Always Show Your Work and The Giant One!
Add and Subtract Fractions
REMEMBER: To Always Show Your Work and The Giant One!
Take out your study guide!!!
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35. 1 Add Fractions 12 4 15 5 10 2 + 3 15 22 15 #11 x 3 = x 3 = x 5 =
Find a common denominator. 15 5
x 3 = 10 2
2) Add the numerators.
x 5 = + 3
x 5 = 15
3) Keep the common denominator the same. 22 7 1 15 15
4) Simplify or reduce. Change improper fractions to mixed #s.
15) 22 15 7

36. - Subtract Fractions 5 x 4 = 20 6 x 4 = 24 1 x 3 = 3 x 3 = 8 24 17 24
#12 5
x 4 = 20 6
x 4 = 24
Always SHOW
YOUR WORK!
This includes the
Giant One. 1
x 3 = 3 -
x 3 = 8 24 17
Giant One 24