Multiples and Factors Dr Y Calhoun Multiples A

Multiples and Factors Dr. Y. Calhoun

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: • • • 4 x 1=4 4 x 2=8 4 x 3 = 12 4 x 4 = 16 4 x 5 = 20 4 x 6 = 24 Counting Numbers So, the multiples of 4 are 4, 8, 12, 16, 20, 24, 28, etc.

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, ____, 15 ____, 18 21 3 6, 9, 12, ____, • ___, 72 • ___, 12 24, 36, 48, 60, ____

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 doubles = done The factors of 16 are 1, 2, 4, 8, 16

What are the factors of 18? 1 2 3 4 5 6 x x x 18 9 6 ? ? 3 The factors are 1, 2, 3, 6, 9, 18 Repeat! Cross it out! We’re done!

What are the factors of 7? 1 x 7 2 x ? ? 3 x ? ? 4 5 6 7 x x ? ? ? 1 The only factors of 7 are 1, 7 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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