The document discusses prime numbers and their identification through the Sieve of Eratosthenes method. It explains the definitions of prime and composite numbers, the historical context of the method, and includes activities for engaging students in learning. Additionally, it poses questions for class discussion regarding the nature of prime numbers.

1. PRIMES, HIGHEST
COMMON FACTOR AND
LEAST COMMON
FACTOR
PRIMES

2. BRAINSTORMING
 I am a number between 1 and 10. I can only be divided by 1 and myself. What am
I?
 I am a number between 10 and 20. I can only be divided by 1 and myself. What
am I?
 I am the smallest number in number series, can only be divided by 1 and myself.
What am I?
PRIME NUMBERS

3. PRIME NUMBERS
Objective: You will learn to identify prime numbers using “Sieve of
Eratosthenes”.
Prime Numbers
 Prime numbers are
numbers that have only 2
factors: 1 and themselves.
 For Example: 2, 3, 5, 7, 11,
19
Composite Number
 A composite number is a
natural number or a
positive integer which has
more than two factors.
 For Example: 4, 6, 8, 10, 34
36

4. PRIME NUMBERS
Objective: You will learn to identify prime numbers using “Sieve of
Eratosthenes”.
Explain why 0 and 1 are neither prime nor composite?
Yasir says that if a whole number is not prime then it
must be composite. Do you agree? Explain your answer.

5. PRIME NUMBERS
Objective: You will learn to identify prime numbers using “Sieve of
Eratosthenes”.
Eratosthenes was the librarian at Alexandria, Egypt in
200 B.C.
Sieve of Eratosthenes

6. PRIME NUMBERS
Objective: You will learn to identify prime numbers using “Sieve of
Eratosthenes”.
 Eratosthenes was a Greek mathematician, astronomer, and
geographer.
 He invented a method for finding prime numbers that is still used
today.
 This method is called Eratosthenes’ Sieve.
 A sieve has holes in it and is used to filter out liquids from solids.
 Similarly, Eratosthenes’s sieve filters out numbers to find the prime
numbers.
Sieve of Eratosthenes

7. PRIME NUMBERS
Objective: You will learn to identify prime numbers using “Sieve of
Eratosthenes”.
ACTIVITY
1. Start at number 2. Put a Circle or highlight it. It is a Prime
Number. 2.
2. Cross out ALL the multiples of 2. (Yes all)
3. Go to the next number 3. Circle or highlight it. It is a Prime
Number.
4. Cross out all the multiples of 3.
5. Move to the next number NOT crossed out (5). It is a Prime
Number.. Repeat the process..
6. Complete this correct for each team member.
7. Show your teacher to WIN THE FIRST 5 POINTS.
8. Then have your first scribe read to you all the Team Rules for the
DE crypto Racer.
Sieve of Eratosthenes

8. PRIME NUMBERS
Objective: You will learn to identify prime numbers using “Sieve of
Eratosthenes”.
Sieve of Eratosthenes

9. PRIME NUMBERS
Objective: You will learn to identify prime numbers using “Sieve of
Eratosthenes”.
Can the product of two prime number be:
a) An odd number?
b) An even number?
c) A prime number?
Explain your answer or give a counter example.
Class Discussion