1. Multiples and Factors
Dr. Y. Calhoun

2. 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.

3. Example: List the multiples of 4:
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

5. Find the Missing Multiples24 30
6, 12, 18, ____, ____
___, 6, 9, 12, ____, ____, 21
___, 24, 36, 48, 60, ____ 15 18 3 72 12

6. 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

7. 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.

8. 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

9. 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!

10. 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.

11. 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

12. Homework Time