Multiples and Factors Lesson 4.1

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.

Example: List the multiples of 4: So, the multiples of 4 are 4, 8, 12, 16, 20, 24, 28, etc. Counting Numbers

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

Find the Missing Multiples 24 30 6, 12, 18, ____, ____ ___, 6, 9, 12, ____, ____, 21 ___, 24, 36, 48, 60, ____ 15 18 3 72 12

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

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

What are the factors of 16? 1 x 16 2 x 8 3 x ?? 4 x 4 3 is not a factor, so cross it out 4 x 4 doubles = done The factors of 16 are 1,2,4,8,16

What are the factors of 18? 1 x 18 The factors are 1,2,3,6,9,18 2 x 9 Repeat! Cross it out! We’re done!

What are the factors of 7? The only factors of 7 are 1,7 1 x 7 2 x ?? This works, but it is a repeat. We are done.

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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