Download Divisibility by 9

August 19, 2015
Lesson 1.2: More Patterns in Division
By the end of this lesson....
You will determine and explain why a number is divisible by
0, 3, 6 and 9
Divisibility rules make math MUCH
easier... and FASTER!
Its like ABC... 123...
Follow the rules and KNOW YOUR
TIMES TABLES
August 19, 2015
Before we start... we need to review some important
terms.
Consecutive - numbers that come one after
the other without any
numbers missing.
Sum - The answer to an addition problem
Factor Pair - A pair of numbers multiplied
together
August 19, 2015
MathLAB
ELBOW PARTNERS
With your ELBOW PARTNER choose 15 consecutive 2 digit
numbers. Use your calculators to determine which numbers are
divisible by 3, 9 and 0.
USE THE CHART IN YOUR WORK BOOK....
2 digit number
Divisible by 3 Yes or No
Divisible by 9 Yes or No Divisible by 0
Yes or No
August 19, 2015
What did you figure out??
Divisibility Test for 3 and 9:
1) List the numbers that are divisible by 3
2) Add up the digits of these numbers.
3) What do you notice?
Numbers that are
Sum of the digits Numbers that are
divisible by 3
Sum of the digits
divisible by 9
August 19, 2015
What did you figure out??
Divisibility Test for 0:
1) What do you notice?
2) What do you think this means?
August 19, 2015
Divisibility Rules for 3, 6, 9 and 0
Divisibility by 3: If the sum of the digits is divisible by 3, the
whole number is divisible by 3
Divisibility by 6: If the number is divisible by 2 and 3 it is also
divisible by 6
Divisibility by 9: If the sum of the digits is divisible by 9, the
whole number is divisible by 9
Divisibility by 0: No numbers are divisible by 0... you can't divide
things into 0 groups!
August 19, 2015
Check for Understanding - Where do these numbers fit?
12
56
42
88
Divisible by 2
453
135
246
Divisible by 3
What can we say about the numbers in the overlapping
region??
728
August 19, 2015
Check for Understanding - Where do these numbers fit?
230
45
1064
506
August 19, 2015
Carroll Diagrams
A Carroll diagram is another way we can sort numbers.
Let's show this by example.
Sort the following number into the proper region
435
789
616
1065
543
800
August 19, 2015
Carroll Diagrams
Sort the following number into the proper region
August 19, 2015
Why Do We Learn Divisibility Rules??
One reason we learn the divisibility rules to help
us find all the factor pairs of a number.
Example:
Find all the factor pairs of 45
Example:
Find all the factor pairs of 120
August 19, 2015
YOUR TURN
1) Assigned work: Pg. 12 & 13 #1, 2, 3, 6, 8 and 9a
2) Complete the Assessment Focus Question and have it
checked by Mrs. French
3) Challenge Questions: Pg. 13 #10
(These are questions you need to be able to complete
and understand if you are looking to get honors mark in
Math)