+

5.3aPrime & Composite

Kim NormanGES2014

+Eratosthene of Cyrene

Born: 276 BC in Cyrene, North Africa (now Shahat, Libia)

Died: 194 BC in Alexandria, Egypt

+ Sieve of Eratosthenes

+Sieve of Eratosthenes

Since 1 is not prime, color it purple

+Sieve of Eratosthenes

Circle the 1st prime number, 2 with your pencilColor every multiple of 2 on your chart

yellow

+Sieve of Eratosthenes

Circle the next prime number, 3 with your pencilColor the multiple of 3 on your chart

red (some multiples of 3, such as 6 and 12, may already be colored yellow. Ignore these and look for the uncolored multiples16

+Sieve of Eratosthenes

Circle the next prime number, 5. Color any uncolored multiples of 5

blue. 6

+Sieve of Eratosthenes

Circle the next prime number, 7.Color any uncolored multiples of 7

green.3

+Sieve of Eratosthenes

Count the uncolored squares on your chartCan you find 25 of them?

If you can, then you have sifted out all of the prime numbers under 100

+Primes & Composites

BrainPopNumbers & Operations

Prime Numbers

+What are Prime Numbers?

?

+What are Prime Numbers?

DefinitionA whole number with exactly two

factors, 1 and itself

+What are Prime Numbers?

CharacteristicsWhole numberOnly has 2 factors

1 and itself

+What are Prime Numbers?

Examples2, 3, 5, 7, 11…

Example: 2 is a prime number2 x 1 (only 2 factors)

Example: 13 is a prime number13 x 1 (only 2 factors)

+What are Prime Numbers?

Non-Examples0, 1, 4, 6, 8, 9…

+Is 1 a Prime Numbers?

How many factors does the number 1 have?Answer = 1

A Prime Number has to have 2 factors So, the number 1 cannot be a Prime Number

+What are Composite Numbers?

?

+What are Composite Numbers?

DefinitionA whole number that has more than

two factors

+What are Composite Numbers?

CharacteristicsWhole numberHas more than 2 factors

+What are Composite Numbers?

Examples 4, 6, 8, 9, 10…

Example: 4 is a composite number1 x 42 x 2(4 has more than 2 factors, it has 3 factors)

Example: 12 is a composite number1 x 122 x 63 x 4(12 has more than 2 factors, it has 6 factors)

+What are Composite Numbers?

Non-Examples0, 1, 2, 3, 5, 7…

+Is 1 a Composite Numbers?

How many factors does the number 1 have?Answer = 1

A Composite Number has to have more than 2 factors So, the number 1 cannot be a Composite

Number

+So 1 is…

Neither Prime

Nor Composite

+Prime, Composite, or Neither…

6

9

7

1

3

5

2

4

10

8

+Prime, Composite, or Neither…

21

60

25

100

32

29

1

81

72

37

+ Finding Prime & Composite

Lets use Connecting Color Tiles

+Rectangles Chart

Number Factors Number of Rectangles

Prime or Composite

1

2

3

4

5

6

7

8

+1 = Neither Prime (only 2 factors)

Nor Composite (more than 2 factors)

1 only has one factor

+2 = Prime

1 x 2 (2 factors)

+3 = Prime

1 x 3 (2 factors)

+4 = Composite

(3 factors)

1 x 4

2 x 2

+5 = Prime

1 x 5 (2 factors)

+6 = Composite

(4 factors)

1 x 6

2 x 3

+7 = Prime

1 x 7 (2 factors)

+8 = Composite

(4 factors)

1 x 8

2 x 4

+

Can You Tell the Difference Between Prime & Composite Numbers?

http://www.321know.com/fra63ax2.htm

+XPMath Primes vs. Composites

XPMath Primes vs. Composites

Monkey Drive

Fruit Splat

King Kong's Prime Numbers

Prime or Composite?

+

Now it’s time for the… Prime and Composite Quiz

Any questions?

Are your ready?

Great, let’s get on IA iTest and get started…

SOL5.3aQuiz