Multiples and Factors

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Multiples and Factors

• Lesson 4.1

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Multiples

• A multiple is formed by multiplying a given
  number by the counting numbers.
• The counting numbers are 1, 2, 3, 4, 5, 6, etc.

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Example List the multiples of 4

• 4 x 1 4
• 4 x 2 8
• 4 x 3 12
• 4 x 4 16
• 4 x 5 20
• 4 x 6 24

So, the multiples of 4 are 4, 8, 12, 16, 20, 24,
28, etc.
Counting Numbers
4
What are the first five multiples of 13?
13 x 1 13 13 x 2 26 13 x 3 39 13 x 4 52 13
x 5 65
13, 26, 39, 52, 65
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Find the Missing Multiples
24
30

• 6, 12, 18, ____, ____
• ___, 6, 9, 12, ____, ____, 21
• ___, 24, 36, 48, 60, ____

15
18
3
72
12
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Factors

• Factors are the numbers you multiply together to
  get a product.
• For example, the product 24 has several factors.
• 24 1 x 24
• 24 2 x 12
• 24 3 x 8
• 24 4 x 6
• SO, the factors are 1, 2, 3, 4, 6, 8, 12, 24

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Finding Factors

• Start with 1 x the number.
• Try 2, 3, 4, etc.
• When you repeat your factors, cross out the
  repeat - youre done at this point.
• If you get doubles (such as 4 x 4), then youre
  done. Repeats or doubles let you know youre
  done.

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What are the factors of 16?
1 x 16
2 x 8
3 x ??
3 is not a factor, so cross it out
4 x 4
doubles done
The factors of 16 are 1,2,4,8,16
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What are the factors of 18?
1 x 18
The factors are 1,2,3,6,9,18
2 x 9
3 x 6
4 x ??
5 x ??
6 x 3
Repeat! Cross it out! Were done!
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What are the factors of 7?
The only factors of 7 are 1,7
1 x 7
2 x ??
3 x ??
4 x ??
5 x ??
6 x ??
7 x 1
This works, but it is a repeat. We are done.
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Prime and Composite Numbers

• Prime numbers are
• numbers that only have
• two factors one, and the
• number itself.
• EXAMPLES
• 3, 5, 7, 11, 31

• Composite numbers
• have more than two
• factors.
• EXAMPLES
• 6, 18, 30, 100

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Homework Time