Fraction IX Least Common Multiple Least Common Denominator

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Fraction IXLeast Common Multiple Least Common
Denominator

• By Monica Yuskaitis

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Product

• The answer to a multiplication problem.

6 X 6 36
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What is the product?
7 X 8 56
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What is the product?
8 X 9 72
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Multiple

• The product of a whole number multiplied times
  any other whole number.

Some multiples of 6 6, 12, 18, 24, 30, 36, 42
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Name some multiples of 5
5, 10, 15, 20, 25, 30, 35
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Name some multiples of 7
7, 14, 21, 28, 35, 42, 49
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Name some multiples of 4
4, 8, 12, 16, 20, 24, 28
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Name some multiples of 9
9, 18, 27, 36, 45, 54, 63
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Common Multiple

• 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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What are some Common Multiples for 2 8?
8, 16, 24, 32, 40, 48, 56
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What are some Common Multiples for 4 6?
12, 24, 36, 48, 56, 60
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What are some Common Multiples for 3 7?
21, 42, 63
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What are some Common Multiples for 5 10?
10, 20, 30, 40, 50, 60
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Least Common Multiple

• The smallest common multiple of a set of two or
  more numbers.

5 5, 10, 15, 20, 25, 30
6 6, 12, 18, 24, 30, 36
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What is the Least Common Multiple of 3 8
3 3, 6, 9, 12, 15, 21, 24
8 8, 16, 24, 32, 40, 48
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What is the Least Common Multiple of 4 8
4 4, 8, 12, 16, 20, 24
8 8, 16, 24, 32, 40, 48
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What is the Least Common Multiple of 6 8
6 6, 12, 18, 24, 30, 36
8 8, 16, 24, 32, 40, 48
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What is the Least Common Multiple of 4 10
4 4, 8, 12, 16, 20, 24
10 10, 20, 30, 40, 50,
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What is the Least Common Multiple of 3 9
3 3, 6, 9, 12, 15, 21,
9 9, 18, 27, 36, 45, 54
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To Add or Subtract Fractions With Unlike
Denominators

• Find the multiples of each denominator.

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5, 10, 15, 20, 25, 30
5
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10, 20, 30, 40, 50
10
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To Add or Subtract Fractions With Unlike
Denominators

• Compare the lists of multiples. Circle the
  common multiples between the two lists.

1
5 5, 10, 15, 20, 25, 30
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10 10, 20, 30, 40, 50
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To Add or Subtract Fractions With Unlike
Denominators

• Use the lowest common multiple as the
  denominator.

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5 5, 10, 15 ,20 ,25 ,30
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10 10, 20, 30, 40, 50
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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
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10 10, 20, 30, 40, 50
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Find the Least Common Denominator or Least Common
Multiple
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2 2, 4, 6, 8, 10, 12
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8 8, 16, 24, 32, 40
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Find the Least Common Denominator or Least Common
Multiple
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10 10, 20, 30, 40,
1

8 8, 16, 24, 32, 40
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Find the Least Common Denominator or Least Common
Multiple
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10 10, 20, 30, 40,
1

4 4, 8, 12, 16, 20,
28
Find the Least Common Denominator or Least Common
Multiple
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2 2, 4, 6, 8, 10,
1

4 4, 8, 12, 16, 20,
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Find the Least Common Denominator or Least Common
Multiple
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2 2, 4, 6, 8, 10, 12
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12 12, 24, 36, 48
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Find the Least Common Denominator or Least Common
Multiple
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3 3, 6, 9, 12, 15
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4 4, 8, 12, 16, 20,
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Find the Least Common Denominator or Least Common
Multiple
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3 3, 6, 9, 12, 15
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5 5, 10, 15, 20, 25,
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Find the Least Common Denominator or Least Common
Multiple
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3 3, 6, 9, 12, 15
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9 9, 18, 27, 36, 45,
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Shortcut for Finding the Least Common Denominator
or Least Common Multiple
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.
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3 will divide evenly into 9, so 9 is your LCD or
LCM.
3
1

9
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Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
2 will divide evenly into 4, so 4 is your LCD or
LCM.
2
1

4
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Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
2 will divide evenly into 10, so 10 is your LCD
or LCM.
2
1

10
36
Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
2 will divide evenly into 12, so 12 is your LCD
or LCM.
2
1

12
37
Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
4 will divide evenly into 8, so 8 is your LCD or
LCM.
4
1

8
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Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
3 will divide evenly into 6, so 6 is your LCD or
LCM.
3
1

6
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Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
3 will divide evenly into 12, so 12 is your LCD
or LCM.
3
1

12
40
Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
3 will divide evenly into 15, so 15 is your LCD
or LCM.
3
1

15
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Shortcut for Finding the Least Common Denominator
or Least Common Multiple
Using the shortcut, what is the LCD or LCM?
1
3 will not divide evenly into 8, so find the
least common multiple.
3
1

8