Prime and Composite Numbers
How can you apply what you know about
multiples and factors to determine prime or
composite numbers?
Vocabulary

Prime - any whole number greater than 1 that has
two factors. 1 and itself

Composite - any whole number greater than 1 that
has more than 2 factors

Multiple - the product of any two whole numbers
(can be found by skip counting)
Factor - the numbers multiplied to find a product
 Factor Pair - the two factors in a multiplication
sentence

array
14
factor pairs
1 x 14
2x7
factors
1, 2, 7, 14
Now let’s see
What
about
skipThere are two
Youhave
could
make
if there
are
You
1 group
ofan
Have you
everof 7
equal
groups
counting
to
find
14
so the
factor
pair
array
and
find
the
any equalheard of a factor
Do you think
How
do I find
so
the
factor
pair
multiples!
would
be 1pairs!
x 14.
factor
you
could
show
groups.
tree?
is
2 x 7. factors?
me with 14?
>
14
2x7
We used 2 x 7 because
the identity property
of multiplication says
1 x 14 and 14 is the
same thing.
We can
there
Now
let’sstop
break
it
First
let’s
recall
the
because 2 and
7 are
down
factoruntil
pairswe
forhave
14.
both
prime.
all primes.
1 x 14 and 2 x 7
>
48
1. Count out
48 counters.
>
_
_ >
12 x 4
2. Break into
3. Write
factor pairs.
4. Try your
factor pairs in
a factor tree.
5. Multiply
your primes to
see if you’re
correct.
6x22x2
>
_
equal groups.
3x2 2 2
How can we
organize this
2
I wonder what a
number tree
would look like if
I had a bigger
number?
Make a chart!
Number
48
<
< _
_
<
< _
48
6x8
3x2 2x4
3 2 2
2x2
Factor
Pairs
•
•
•
•
•
1 x 48
2 x 24
3 x 16
4 x 12
6x8
Factors
Prime or Composite
1, 2, 3, 4, 6, 8, 12, 16, 24, 48 Composite
No matter the
factor pair you
get the same
primes.
I wonder if I used
another factor pair
would my number
tree look the
same?
You give it a try!
Number
Factor
Pairs
Factors
Prime or Composite
36
Use the factors
in a number
tree.
Find equal
groups.
Find the
factor
pairs.
45
24
18
72
Make arrays.
Use manipulatives
to help you if you
need them.
Go to Stations
Teacher
Application
Computers
Flash Cards
Table 1
Table 2
Table 3
Table 4
Table 2
Table 3
Table 4
Table 1
Table 3
Table 4
Table 1
Table 2
Table 4
Table 1
Table 2
Table 3