How do you determine if a number is a prime or composite number?
For example:Is 15 a prime or composite number?
You will learn how to determine if a number is prime or
composite number by using area models.
Let’s Review
2x 3
=x 2
3
Multiplication can be shown as an area model.
A Common Mistake
Not all odd numbers are prime numbers.
5 is ODD & a prime9 is ODD & is NOT prime
Core LessonA prime number has ONLY one set of factor
pairs (1 and itself).
5:
1x59:
1x9
3x3
prime composite
Core LessonIs 15 a prime or composite number?
15: 1 x 15
3 x 5
In this lesson you have learned how to determine if a number is prime or composite by using
area models.
Guided Practice17
Prime or Composite?
1 x 17= 17
Extension Activities
Look at these numbers: 10, 11, and 12
Which ones are prime?
Which ones are composite?
Extension Activities
Is 81 a prime or composite number? How do you know?
Extension Activities
What other strategies can you use to find out if a number is prime or composite?
Extension Activities
Can a multiple of a number be a prime number? Explain your thinking.
Quick Quiz
16: Prime number or Composite number?
Find all the factor pairs for 13. Then decide if it is a prime or composite number.