4.3 Greatest Common Factors (GCF)

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4.3 Greatest Common Factors (GCF)

• I can find the greatest common factor of a set of
  numbers

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Review

• A factor is number that is multiplied by another
  number to get a product

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The greatest common factor is the largest factor
that two or more numbers share.
Factors of 24 Factors of 36 Common factors
1,
2,
3,
4,
6,
8,
12,
24
1,
2,
3,
4,
6,
9,
12,
18,
36
1, 2, 3, 4, 6,
12
The greatest common factor (GCF) of 24 and 36 is
12. Example 1 shows three different methods for
finding the GCF.
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Additional Example 1A Finding the GCF Find the
GCF of the set of numbers.
28 and 42 Method 1 List the factors. factors of
28 factors of 42
List all the factors.
1,
2,
14,
7,
28
4,
7,
1,
3,
2,
42
6,
21,
14,
Circle the GCF.
The GCF of 28 and 42 is 14.
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Check It Out Example 1A Find the GCF of the set
of numbers.
18 and 36 Method 1 List the factors. factors of
18 factors of 36
List all the factors.
1,
2,
9,
6,
18
3,
6,
1,
3,
2,
36
4,
12,
9,
Circle the GCF.
18,
The GCF of 18 and 36 is 18.
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Try on your Own

• 16 28
• 24 56

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Guided using Distributive Property

• 15 25
• 36 72

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Try on your own

• 10 90
• 45 72

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LCM

• LCM Least Common Multiple The smallest number,
  other than zero, that is a multiple of two or
  more given numbers

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Guided Practice

• 5 6
• 9 11

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Try on Your own

• 3 7
• 4 6