Multiples and Factors Lesson 4.1
Mar 27, 2015
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