prime and composite numbers how can you apply what you know about multiples and factors to determine...
TRANSCRIPT
Prime and Composite Numbers
How can you apply what you know about multiples and factors to determine prime or composite
numbers?
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
How do I find factors?
You could make an array and find the factor pairs!
What about skip counting to find
multiples!
Have you ever heard of a factor
tree?
Do you think you could
show me with 14?
14array
You have 1 group of 14 so the factor
pair would be 1 x 14.
Now let’s see if there
are any equal
groups.
There are two equal groups of 7 so the factor pair is 2 x 7.
factor pairs1 x 142 x 7
factors1, 2, 7, 14
What
abou
t thos
e
fact
or tr
ees?
First let’s recall the factor pairs
for 14.
1 x 14 and 2 x 7
Umm
…m
aybe
we
shou
ld a
sk th
e
class
.Aweso
me! N
ow
what? Now let’s break it
down until we have all primes.
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.
We can stop there because 2 and 7 are both prime.
I wonder what a number tree would look like if I had a bigger
number?
481. Count out 48 counters.
2. Break into equal groups.3. Write factor pairs.
4. Try your factor pairs in a factor tree.
>12 x 4
> >
6 x 2
2 x 2
> _ __
3 x 2
2 2 2
5. Multiply your primes to see if you’re correct.
How can we organize this
Make a chart!Number Factor
PairsFactors 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
I wonder if I used another
factor pair would my
number tree look the same?
48<
6 x 8< <
3 x 2 2 x 4_ _ _ <
3 2 2 2 x 2
No matter the factor
pair you get the same primes.
You give it a try!
Find equal groups. Make
arrays.
Find the factor pairs.
Use the factors in a
number tree.
Number Factor Pairs
Factors Prime or Composite
36
45
24
18
72
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