Transcript Prime and Composite Numbers - Mendenhall-Jr-PLC

PowerPoint created by
Parsheena Berch
Resource: JBHM material
Pictures: Google Images
Prime and
Composite
Numbers
Bell Ringer:
• Page 35 in JBHM binder (DOK 3)
Focus/Introduction:
• 1d: Model and distinguish between prime and
composite numbers. (DOK 1)
• Prime and composite numbers help us to work
with numbers better. This will help us next
week when we work with factors and
multiples. Also, this will help when we work
with fractions.
• We can “tell” if a certain number can be
divided by another number. For example, we
know that 655 is divisible by 5 because the
number ends with a five. Quickly, go over the
divisibility rules again for 2, 3, 4, 5, 6, 9, and
10.
Divisibility Rules: A number is divisible
by ___ if…
• 2 – The number is an even number, ending in
2, 4, 6, 8, 0.
Example:
• 124: It ends in 4, so it is divisible by 2.
• 124 ÷ 2 = 62
Divisibility Rules: A number is divisible
by ___ if…
• 3 – The sum of the digits is divisible by 3.
Example:
• 150: The sum of the digits, 1 + 5 + 0 = 6, is
divisible by 3, so 150 is divisible by 3.
• 150 ÷ 3 = 50
Divisibility Rules: A number is divisible
by ___ if…
• 4 – The number is even and the last 2 digits
form a number that is divisible by 4.
Example:
• 724: It is even, and the last two digits, 24, is
divisible by 4, so 724 is divisible by 4.
• 724 ÷ 4 = 181
Divisibility Rules: A number is divisible
by ___ if…
• 5 – The number ends in 0 or 5.
Example:
• 105: It ends in 5, so 105 is divisible by 5.
• 105 ÷ 5 = 21
Divisibility Rules: A number is divisible
by ___ if…
• 6– The number is even, and the sum of its
digits is divisible by 3.
Example:
• 450: It is even and the sum of the digits, 4 + 5
+ 0 = 9, is divisible by 3, so 450 is divisible by
6. In other words, if the rule for 2 and the rule
for 3 work, the number is divisible by 6.
• 450 ÷ 6 = 75
Divisibility Rules: A number is divisible
by ___ if…
• 7 and 8 – These rules are too complicated to
actually be shortcuts.
Divisibility Rules: A number is divisible
by ___ if…
• 9 – The sum of the digits is divisible by 9.
Example:
• 450: The sum of the digits, 4 + 5 + 0 = 9, is
divisible by 9, so 450 is divisible by 9.
• 450 ÷ 9 = 50
Divisibility Rules: A number is divisible
by ___ if…
• 10 –The number ends in 0.
Example:
• 1250: It ends in 0, so 1250 is divisible by 10.
• 1250 ÷ 10 = 125
Guided Practice: (DOK 1)
• Composite Number- a natural number that
has more than two factors.
• Examples: the factors of 8 are 1, 2, 4, and 8.
Since there are more than two factors, 8 is
composite.
• More Examples…
• Prime Numbers- a number that has only two
factors, 1 and itself. The GCF of two prime
numbers is 1.
• Examples: The only factors of 2 are 1 and 2.
Since there are only two factors, it is prime.
• More Examples…
Independent Practice: (DOK 2)
• Handout #1 Page 108
• I am going to guide you through the steps to
this activity. You must pay attention to
everything I say. If you don’t, you will mess
your page up.
• Cross out #1 because it is neither prime nor
composite.
• Circle #2, the first prime number, and shade all
multiples of 2.
• Circle #3, the next prime number, and shade
all multiples of 3.
• What is your method to finding the multiples?
• Circle #5 and shade all multiples of 5.
• Circle #7 and shade all multiples of 7.
• Predict what will be the first multiple of 7.
• Circle the next prime number, 11, and then
predict what the next unmarked number is.
• What is left?
• Prime numbers
Closure:
• Define and give examples of each:
• Prime numbers: _____________________
• Composite numbers: ____________________
• Superprime numbers: ___________________