Transcript Divisibility

Divisibility
Everyday Math Lesson 1.5
Lesson Objectives
• I can find the factors of a
number.
• I can explore relationships
between the operations of
multiplication and division.
• I can use divisibility rules to
solve problems.
Mental Math
10 x 8
6x3
8*4
4x3
3*9
8*6
10 x 4
9x3
8*8
5x6
7*3
9*7
4x7
6x8
7*7
6x4
Math Message
Solve problems 1 and 2 at
the top of Journal page 13.
Homework Check
• Please get out your Study
Link 1.4.
• With a partner at your
table, compare your
answers and resolve any
differences.
Math Message Follow-Up
• How did you know the
numbers you circled are
divisible by 2?
–ALL even numbers are
divisible by 2.
Vocabulary
• Add the following
vocabulary words to your
Unit 1 vocabulary chart:
–Remainder
–Sum
–Quotient
Using a Calculator to Test
for Divisibility
• Find the symbol on your calculator
that says Int÷
• You will use this key instead of the ÷
key to check for divisibility.
• If the quotient has a remainder when
dividing, that number is NOT divisible
by the number you’re testing.
Let’s Try It!
Do the following examples in your Work Journal
• Example: Is 27 divisible by 5?
– On your calculator, type in 27 Int÷ 5
and then Enter.
– Does the quotient have a remainder?
– If it does have a remainder, then 27
is NOT divisible by 5.
Example #2
• Is 27 divisible by 9?
– On your calculator, type in 27 Int÷9
and then Enter.
– Does the quotient have a remainder?
– If it doesn’t, then 27 IS divisible by
9.
Your Turn!
• With your assigned
partner, please complete
page 13.
• You will have 15 minutes to
complete this page.
Divisibility Rules
• How can we know that a number is
divisible by 2 without actually
doing the division?
• Can you tell whether a number is
divisible by 10 without dividing?
• Can you tell whether a number is
divisible by 3 without dividing?
Divisibility Rules (cont.)
• A number is divisible by 3 if the
SUM of its digits is divisible by 3.
– Is 237 divisible by 3? (use your
calculator)
– Is 415 divisible by 3? (use your
calculator)
Your Turn!
• With your assigned partner,
please complete Journal Page 14.
• When you hear the bell, please
return to your seat and be ready
to share your answers.
Let’s Play Factor Captor
• Open your SRB to page 306, read
silently about how to play
“Factor Captor”
• With your assigned partner, you
will have 15 minutes to play as
many games of Factor Captor as
you can.
Math Boxes & Study Link
• For the rest of class, work on
Math Boxes 5.1 on page 15 of your
Student Journal.
• If you finish with Math Boxes, you
may come get a Study Link 5.1
homework assignment.