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:

• 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

• 6, 12, 18, ____, ____

• ___, 6, 9, 12, ____, ____, 21

• ___, 24, 36, 48, 60, ____

24 30

3 15 18

12 72

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 162 x 83 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

What are the factors of 18?

1 x 182 x 93 x 64 x ??5 x ??6 x 3 Repeat! Cross it out!

We’re done!

The factors are 1,2,3,6,9,18

What are the factors of 7?

1 x 72 x ??3 x ??

4 x ??5 x ??6 x ??7 x 1 This works, but it is a repeat. We are

done.

The only factors of 7 are 1,7

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