Transcript Topic 3 Review and Reteach

Are you ready?
Here are the
concepts we’re
covering in math.
Let’s see what you know!
Mrs. Flynn’s Topic 3 Math Review
Multiplying by Multiples of Ten
4 X 20 = ?
Look for the basic fact to
help you.
4 X 2 tens = 8 tens
So…
4 X 20 = 80
Basic fact
Basic fact
Basic fact
Practice Multiplying Tens
1. 3 X 2 tens = 6 tens (60)
2. 6 X 5 tens = 30 tens (300)
3. 8 X 6 tens = 48 tens (480)
4.
5.
6.
7.
7
7
6
4
X
X
X
X
20
80
90
50
=
=
=
=
140
560
540
200
Nicole builds 3 birdhouses in an hour
& works 40 hours weekly.
How many birdhouses does she
make each week?
3 birdhouses X 40 hours =
There are 20 chickens on John’s farm.
Each lays 2 eggs each day.
How many eggs can John
collect each week?
2 eggs X 20 chickens X 7 days =
Multiplying Using Patterns
Look for the basic fact to help you.
3 X 3 hundreds = 9 hundreds
So…
Basic fact
3 X 300 = 900
Basic fact
Basic fact
Multiplication Patterns
Use the same idea to help you multiply
larger numbers.
6 X 4 = 24
6 X 40 = 240
6 X 400 = 2,400
6 X 4,000 = 24,000
Practice! Find each product.
1.
5 X 90 =
450
2. 70 X 700 = 49,000
3. 6 X 5,000 = 30,000
4. 600 X 70 = 42,000
5. 8,000 X 3 = 24,000
Estimate means…
to find a number
close to the exact
number.
Rounding to Estimate
Products
Cheyenne collects books. She has 8 boxes.
Each box holds about 38 books. How many
books does she have?
(38 rounds to 40)
Rounding to Estimate
Products
Christian collects books. He has 18 shelves.
Each shelf holds about 115 books. About how
many books does he have?
(115 rounds to 100)
(18 rounds to 20)
Rounding to Estimate
Products
Corey collects football cards. He has 5 albums.
Each album holds 45 cards. About how many
football cards does Corey have?
(45 rounds to 50)
Now it’s your turn!
1.
2.
3.
4.
5.
6.
7.
567 X 5
674 X 22
7,881 X 6
3,580 X 3
6 X 251
4 X 3,679
72 X 1,814
600 X 5 = 3,000
700 X 20 = 14,000
8,000 X 6 = 48,000
4,000 X 3 = 12,000
6 X 300 = 1,800
4 X 4,000 = 16,000
70 X 2,000 = 140,000
Distributive Property with Arrays
What is an array?
An array is an arrangement of
objects into rows and columns.
5
rows
of 1
5
rows
of 10
Practice! Draw arrays to help.
1. 73 X 7
70 X 7 = 490
3 X 7 = 21
490 + 21 = 511
2. 35 X 6
30 X 6 = 180
5 X 6 = 30
180 + 30 = 210
3. 59 X 4
50 X 4 = 200
9 X 4 = 36
200 + 36 = 236
4. 46 X 9
40 X 9 = 360
6 X 9 = 54
360 + 54 = 414
5. 26 X 3
20 X 3 = 60
6 X 3 = 18
60 + 18 = 78
Multiplication with Regrouping
Step One: Multiply the ones & regroup.
+3
Multiplication with Regrouping
Step Two: Multiply the tens & add the
extra tens.
+3
Multiplication with Regrouping
Try some with me!
+2
+2=
23
Multiplication with Regrouping
Try some with me!
+1
+1=
36
Multiplication with Regrouping
Try some with three digits!
+1 +5
+5=
+1=
17
49
Multiplication with Regrouping
Try some with three digits!
+1 +2
+2=
+1=
18
25
Multiplication with Regrouping
Try some multiplication with money!
+3 +2
+2=
+3=
37
10
Multiplication with Regrouping
Try some multiplication with money!
+3 +7
+7
+7=
+7=
+3=
79
39
11
What is the Associative Property?
When the grouping of factors is
changed, the product remains the
same.
What is the Commutative Property?
When the order of factors is changed,
the product remains the same.
Multiplying 3 Factors
The parentheses tell which factors to
multiply first.
I know
you’re going
to do this on
a piece of
paper, right?
Multiplying 3 Factors
The parentheses tell which factors to
multiply first.
And you can
do this in
your head,
right?
Multiplying 3 Factors
The parentheses tell which factors to
multiply first.
It’s all
switched up,
but it’s the
same idea…
Multiplying 3 Factors
If there are no parentheses, multiply
the smaller numbers first.
Okay.
NO
PROBLEMO,
No
parentheses?
MAN!
Pencil, paper, and practice!
1. 6 X 6 X 3 =
18 X 6 = 108
2. 3 X 9 X 1 =
3X9=
3. 8 X 5 X 6 =
30 X 8 = 240
27
4. 4 X 3 X 11 = 11 X 12 = 132
5. 7 X 0 X 21 = 0 X 21 = 0
Problem Solving Fun!
To raise money for the food drive, Kaitlyn sold 5
boxes of cards. Connor sold 3 boxes of candy
bars. If a box of cards costs $2.99 and a box of
candy bars costs $5.25, how much did they earn?
+4 +4
+1
2 Digit by 2
Digit
Multiplication
36
X 23
Multiply the ones.
36
X 23
3 X 6 = 18 Regroup the ten.
3 X 3 = 9 and one more is 10.
1
36
X 23
108
36
X 23
108
1
Cross out the 1 after you use it.
NOW THINK:
“I am multiplying 36 X 20.”
36
X 23
108
st
1
THINK:
“I am multiplying by tens
so I need a zero.”
36
X 23
108
0
2 X 6 = 12
Put down
the 2 and
regroup
the 1.
1
36
X 23
108
20
1
1
36
X 23
108
720
1
2X3=6
and
6+1=7
1
Cross out
the
number
you
regrouped
after you
add it.
1
36
X 23
108
720
Since multiplication is a form of
addition, we need to group our
answers together.
Add the two partial products
to get the final product.
8+0=8
0+2=2
1+7=8
36
X 23
108
+ 720
828
Exponents
The number that is repeatedly
multiplied is called the ___________.
The _________________ shows the
number of times the base is used as a
factor.
The base is multiplied 3X
Write in Exponential Notation
1. Four squared =
2. Two cubed =
3. 5 X 5 X 5 X 5 =
4. 4 X 4 X 4 X 4 X 4 =
5. 6 to the 5th power =
Write in Standard Form
1. Four squared =
=
4 x 4 = 16
2. Two cubed =
=
8
3. 5 X 5 X 5 X 5 =
=
625
4. 4 X 4 X 4 X 4 X 4 =
=
1,024
5. 6 to the 3rd power =
=
216