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:
4x1=4 4x2=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 - 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. What are the factors of 16? 1 2
3 4 x x x x 16 8 ?? 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 x x x 18 9 6 ?? ?? 3 The factors are 1,2,3,6,9,18
Repeat! Cross it out! Were done! What are the factors of 7? 1 2 3 4 5 6 7 x x x
x x x x 7 ?? ?? ?? ?? ?? 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 Homework Time