Let’s see what you know!Mrs. Flynn’s Topic 3 Math Review

Are you ready?

Here are the concepts we’re

covering in math.

Multiplying by Multiples of Ten 4 X 20 = ?

Look for the basic fact to help you.

4 X 2 tens = 8 tensSo… 4 X 20 = 80

Basic fact Basic fact Basic fact

Practice Multiplying Tens

1. 3 X 2 tens = 2. 6 X 5 tens =3. 8 X 6 tens =

4. 7 X 20 =5. 7 X 80 =6. 6 X 90 =7. 4 X 50 =

6 tens 30 tens 48 tens

140560540200

(60) (300) (480)

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… 3 X 300 = 900

Basic fact 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 =

2. 70 X 700 =

3. 6 X 5,000 =

4. 600 X 70 =

5. 8,000 X 3 =

450

49,000

30,000

42,000

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 ProductsCorey 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. 567 X 52. 674 X 223. 7,881 X 64. 3,580 X 35. 6 X 2516. 4 X 3,6797. 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 10

5 rows of 1

Practice! Draw arrays to help.

1. 73 X 7

2. 35 X 6

3. 59 X 4

4. 46 X 9

5. 26 X 3

70 X 7 = 490

30 X 6 = 180

50 X 4 = 200

40 X 9 = 360

20 X 3 = 60

3 X 7 = 21

5 X 6 = 30

9 X 4 = 36

6 X 9 = 54

6 X 3 = 18

490 + 21 = 511

180 + 30 = 210

200 + 36 = 236

360 + 54 = 414

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+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!+5

+ 5 = 17

+1

+ 1 = 49

Multiplication with Regrouping

Try some with three digits!+2

+ 2 = 18

+1

+ 1 = 25

Multiplication with Regrouping

Try some multiplication with money!+2

+ 2 = 37

+3

+ 3 = 10

Multiplication with Regrouping

Try some multiplication with money!+7

+ 7 = 79

+7

+ 7 = 39

+ 3 = 11

+3

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.

NO PROBLEMO,

MAN!

Okay.No

parentheses?

Pencil, paper, and practice!

1. 6 X 6 X 3 =

2. 3 X 9 X 1 =

3. 8 X 5 X 6 =

4. 4 X 3 X 11 =

5. 7 X 0 X 21 =

18 X 6 =

3 X 9 =

30 X 8 =

11 X 12 =

0 X 21 =

108

27

240

132

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.

36 X 23 108

1

36 X 23 108Cross out the 1 after you use it.

1

NOW THINK:“I am multiplying 36 X 20.”

36 X 23 108

1st THINK:

“I am multiplying by tens so I need a zero.”

36 X 23 108 0

36 X 23 108 20

112 X 6 = 12

Put down the 2 and regroup the 1.

36 X 23 108 720

11

2 X 3 = 6

and

6 + 1 = 7

36 X 23 108 720

11

Cross out the number you regrouped after you add it.

Since multiplication is a form ofaddition, we need to group our

answers together.

Add the two partial productsto get the final product.

36 X 23 108 + 720 828

8 + 0 = 8

0 + 2 = 2

1 + 7 = 8

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 = =

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 3rd power = =

4 x 4 = 16

1,024

625

8

216