1. Prime and Composite Numbers
How can you apply what you know about multiples and factors to determine prime or composite numbers?

2. Vocabulary Prime - Composite - Multiple - Factor - Factor Pair -
any whole number greater than 1 that has two factors. 1 and itself
any whole number greater than 1 that has more than 2 factors
the product of any two whole numbers (can be found by skip counting)
the numbers multiplied to find a product
the two factors in a multiplication sentence

3. 14 array factor pairs factors 1, 2, 7, 14 1 x 14 2 x 7
Now let’s see if there are any equal groups.
What about skip counting to find multiples!
There are two equal groups of 7 so the factor pair is 2 x 7.
You have 1 group of 14 so the factor pair would be 1 x 14.
You could make an array and find the factor pairs!
Have you ever heard of a factor tree?
Do you think you could show me with 14?
How do I find factors?

4. 14
>
2 x 7
We used 2 x 7 because the identity property of multiplication says
1 x 14 and 14 is the same thing.
Now let’s break it down until we have all primes.
We can stop there because 2 and 7 are both prime.
Umm…maybe we should ask the class.
What about those factor trees?
Awesome! Now what?
First let’s recall the factor pairs for 14.
1 x 14 and 2 x 7

5. > > > > _ _ _ 48 12 x 4 6 x 2 2 x 2 3 x 2 2 2 2
1. Count out 48 counters.
12 x 4
>
>
2. Break into equal groups.
6 x 2
2 x 2
> _ _ _
3 x 2 2 2 2
3. Write factor pairs.
I wonder what a number tree would look like if I had a bigger number?
How can we organize this
4. Try your factor pairs in a factor tree.
5. Multiply your primes to see if you’re correct.

6. No matter the factor pair you get the same primes.
Make a chart!
Number
Factor Pairs
Factors
Prime or Composite 48
1 x 48
2 x 24
3 x 16
4 x 12
6 x 8
1, 2, 3, 4, 6, 8, 12, 16, 24, 48
Composite
No matter the factor pair you get the same primes. 48
I wonder if I used another factor pair would my number tree look the same?
<
6 x 8
<
<
3 x 2
2 x 4 _ _ _
< 3 2 2
2 x 2

7. You give it a try! Use manipulatives to help you if you need them.
Number
Factor Pairs
Factors
Prime or Composite 36 45 24 18 72
Find the factor pairs.
Use the factors in a number tree.
Find equal groups.
Make arrays.
Use manipulatives to help you if you need them.

8. Go to Stations Teacher Application Computers Flash Cards Table 1