Learning Objectives
 Use multiplication notation
 Model multiplication of whole numbers
 Multiply whole numbers
 Translate word phrases to math notation
 Multiply whole numbers in applications
Be Prepared 1.3
Before you get started, take this readiness quiz.
 Add: $\mathrm{1,683}+479.$
If you missed this problem, review Example 1.21.  Subtract: $605321.$
If you missed this problem, review Example 1.33.
Use Multiplication Notation
Suppose you were asked to count all these pennies shown in Figure 1.11.
Would you count the pennies individually? Or would you count the number of pennies in each row and add that number $3$ times.
Multiplication is a way to represent repeated addition. So instead of adding $8$ three times, we could write a multiplication expression.
We call each number being multiplied a factor and the result the product. We read $3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}8$ as three times eight, and the result as the product of three and eight.
There are several symbols that represent multiplication. These include the symbol $\times $ as well as the dot, $\xb7$, and parentheses $(\phantom{\rule{0.2em}{0ex}}\text{).}$
Operation Symbols for Multiplication
To describe multiplication, we can use symbols and words.
Operation  Notation  Expression  Read as  Result 

$\text{Multiplication}$  $\times $ $\xb7$ $\left(\phantom{\rule{0.2em}{0ex}}\right)$ 
$3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}8$ $3\xb78$ $3(8)$ 
$\text{three times eight}$  $\text{the product of 3 and 8}$ 
Example 1.39
Translate from math notation to words:
 ⓐ $7\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}6$
 ⓑ $12\xb714$
 ⓒ $6(13)$
Solution
 ⓐ We read this as seven times six and the result is the product of seven and six.
 ⓑ We read this as twelve times fourteen and the result is the product of twelve and fourteen.
 ⓒ We read this as six times thirteen and the result is the product of six and thirteen.
Try It 1.77
Translate from math notation to words:
 ⓐ $8\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}7$
 ⓑ $18\xb711$
Try It 1.78
Translate from math notation to words:
 ⓐ $(13)(7)$
 ⓑ $5(16)$
Model Multiplication of Whole Numbers
There are many ways to model multiplication. Unlike in the previous sections where we used $\text{base10}$ blocks, here we will use counters to help us understand the meaning of multiplication. A counter is any object that can be used for counting. We will use round blue counters.
Example 1.40
Model: $3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}8.$
Solution
To model the product $3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}8,$ we’ll start with a row of $8$ counters.
The other factor is $3,$ so we’ll make $3$ rows of $8$ counters.
Now we can count the result. There are $24$ counters in all.
$3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}8=24$
If you look at the counters sideways, you’ll see that we could have also made $8$ rows of $3$ counters. The product would have been the same. We’ll get back to this idea later.
Try It 1.79
Model each multiplication: $4\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}6.$
Try It 1.80
Model each multiplication: $5\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}7.$
Multiply Whole Numbers
In order to multiply without using models, you need to know all the one digit multiplication facts. Make sure you know them fluently before proceeding in this section.
Table 1.4 shows the multiplication facts. Each box shows the product of the number down the left column and the number across the top row. If you are unsure about a product, model it. It is important that you memorize any number facts you do not already know so you will be ready to multiply larger numbers.
×  0  1  2  3  4  5  6  7  8  9 

0  0  0  0  0  0  0  0  0  0  0 
1  0  1  2  3  4  5  6  7  8  9 
2  0  2  4  6  8  10  12  14  16  18 
3  0  3  6  9  12  15  18  21  24  27 
4  0  4  8  12  16  20  24  28  32  36 
5  0  5  10  15  20  25  30  35  40  45 
6  0  6  12  18  24  30  36  42  48  54 
7  0  7  14  21  28  35  42  49  56  63 
8  0  8  16  24  32  40  48  56  64  72 
9  0  9  18  27  36  45  54  63  72  81 
What happens when you multiply a number by zero? You can see that the product of any number and zero is zero. This is called the Multiplication Property of Zero.
Multiplication Property of Zero
The product of any number and $0$ is $0.$
Example 1.41
Multiply:
 ⓐ $0\xb711$
 ⓑ $(42)0$
Solution
ⓐ  $0\xb711$ 
The product of any number and zero is zero.  $0$ 
ⓑ  $(42)0$ 
Multiplying by zero results in zero.  $0$ 
Try It 1.81
Find each product:
 ⓐ $0\xb719$
 ⓑ $(39)0$
Try It 1.82
Find each product:
 ⓐ $0\xb724$
 ⓑ $(57)0$
What happens when you multiply a number by one? Multiplying a number by one does not change its value. We call this fact the Identity Property of Multiplication, and $1$ is called the multiplicative identity.
Identity Property of Multiplication
The product of any number and $1$ is the number.
Example 1.42
Multiply:
 ⓐ $(11)1$
 ⓑ $1\xb742$
Solution
ⓐ  $(11)1$ 
The product of any number and one is the number.  $11$ 
ⓑ  $1\xb742$ 
Multiplying by one does not change the value.  $42$ 
Try It 1.83
Find each product:
 ⓐ $(19)1$
 ⓑ $1\xb739$
Try It 1.84
Find each product:
 ⓐ$(24)(1)$
 ⓑ $1\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}57$
Earlier in this chapter, we learned that the Commutative Property of Addition states that changing the order of addition does not change the sum. We saw that $8+9=17$ is the same as $9+8=17.$
Is this also true for multiplication? Let’s look at a few pairs of factors.
When the order of the factors is reversed, the product does not change. This is called the Commutative Property of Multiplication.
Commutative Property of Multiplication
Changing the order of the factors does not change their product.
Example 1.43
Multiply:
 ⓐ $8\xb77$
 ⓑ $7\xb78$
Solution
ⓐ  $8\xb77$ 
Multiply.  $56$ 
ⓑ  $7\xb78$ 
Multiply.  $56$ 
Changing the order of the factors does not change the product.
Try It 1.85
Multiply:
 ⓐ $9\xb76$
 ⓑ $6\xb79$
Try It 1.86
Multiply:
 ⓐ $8\xb76$
 ⓑ $6\xb78$
To multiply numbers with more than one digit, it is usually easier to write the numbers vertically in columns just as we did for addition and subtraction.
We start by multiplying $3$ by $7.$
We write the $1$ in the ones place of the product. We carry the $2$ tens by writing $2$ above the tens place.
Then we multiply the $3$ by the $2,$ and add the $2$ above the tens place to the product. So $3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}2=6,$ and $6+2=8.$ Write the $8$ in the tens place of the product.
The product is $81.$
When we multiply two numbers with a different number of digits, it’s usually easier to write the smaller number on the bottom. You could write it the other way, too, but this way is easier to work with.
Example 1.44
Multiply: $15\xb74.$
Solution
Write the numbers so the digits $5$ and $4$ line up vertically.  $\begin{array}{c}\hfill 15\phantom{\rule{0.5em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times \phantom{\rule{0.3em}{0ex}}4}\end{array}$ 
Multiply $4$ by the digit in the ones place of $15.$ $4\cdot 5=20.$  
Write $0$ in the ones place of the product and carry the $2$ tens.  $\begin{array}{c}\hfill \stackrel{2}{1}5\phantom{\rule{0.5em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times \phantom{\rule{0.3em}{0ex}}4}\\ \hfill 0\phantom{\rule{0.5em}{0ex}}\end{array}$ 
Multiply $4$ by the digit in the tens place of $15.$ $4\cdot 1=4$. Add the $2$ tens we carried. $4+2=6$. 

Write the $6$ in the tens place of the product.  $\begin{array}{c}\hfill \stackrel{2}{1}5\phantom{\rule{0.5em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times \phantom{\rule{0.3em}{0ex}}4}\\ \hfill 60\phantom{\rule{0.5em}{0ex}}\end{array}$ 
Try It 1.87
Multiply: $64\xb78.$
Try It 1.88
Multiply: $57\xb76.$
Example 1.45
Multiply: $286\xb75.$
Solution
Write the numbers so the digits $5$ and $6$ line up vertically.  $\begin{array}{c}\hfill 286\phantom{\rule{0.5em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times \phantom{\rule{0.3em}{0ex}}5}\end{array}$ 
Multiply $5$ by the digit in the ones place of $286.$ $5\cdot 6=30.$  
Write the $0$ in the ones place of the product and carry the $3$ to the tens place.Multiply $5$ by the digit in the tens place of $286.$ $5\cdot 8=40$.  $\begin{array}{}\\ \hfill 2\stackrel{3}{8}6\phantom{\rule{0.5em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times \phantom{\rule{0.3em}{0ex}}5}\\ \hfill 0\phantom{\rule{0.2em}{0ex}}\end{array}$ 
Add the $3$ tens we carried to get $40+3=43$. Write the $3$ in the tens place of the product and carry the 4 to the hundreds place. 
$\begin{array}{c}\hfill \stackrel{4}{2}\stackrel{3}{8}6\phantom{\rule{0.5em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times \phantom{\rule{0.3em}{0ex}}5}\\ \hfill 30\phantom{\rule{0.2em}{0ex}}\end{array}$ 
Multiply $5$ by the digit in the hundreds place of $286.$ $5\cdot 2=10.$ Add the $4$ hundreds we carried to get $10+4=14.$ Write the $4$ in the hundreds place of the product and the $1$ to the thousands place. 
$\begin{array}{c}\hfill \stackrel{4}{2}\stackrel{3}{8}6\phantom{\rule{0.5em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times \phantom{\rule{0.3em}{0ex}}5}\\ \hfill \mathrm{1,430}\phantom{\rule{0.2em}{0ex}}\end{array}$ 
Try It 1.89
Multiply: $347\xb75.$
Try It 1.90
Multiply: $462\xb77.$
When we multiply by a number with two or more digits, we multiply by each of the digits separately, working from right to left. Each separate product of the digits is called a partial product. When we write partial products, we must make sure to line up the place values.
How To
Multiply two whole numbers to find the product.
 Step 1. Write the numbers so each place value lines up vertically.
 Step 2.
Multiply the digits in each place value.
 Work from right to left, starting with the ones place in the bottom number.
 Multiply the bottom number by the ones digit in the top number, then by the tens digit, and so on.
 If a product in a place value is more than $9,$ carry to the next place value.
 Write the partial products, lining up the digits in the place values with the numbers above.
 Repeat for the tens place in the bottom number, the hundreds place, and so on.
 Insert a zero as a placeholder with each additional partial product.
 Work from right to left, starting with the ones place in the bottom number.
 Step 3. Add the partial products.
Example 1.46
Multiply: $62(87).$
Solution
Write the numbers so each place lines up vertically.  
Start by multiplying 7 by 62. Multiply 7 by the digit in the ones place of 62. $7\cdot 2=14.$ Write the 4 in the ones place of the product and carry the 1 to the tens place.  
Multiply 7 by the digit in the tens place of 62. $7\cdot 6=42.$ Add the 1 ten we carried. $42+1=43$. Write the 3 in the tens place of the product and the 4 in the hundreds place.  
The first partial product is 434.  
Now, write a 0 under the 4 in the ones place of the next partial product as a placeholder since we now multiply the digit in the tens place of 87 by 62. Multiply 8 by the digit in the ones place of 62. $8\cdot 2=16.$ Write the 6 in the next place of the product, which is the tens place. Carry the 1 to the tens place.  
Multiply 8 by 6, the digit in the tens place of 62, then add the 1 ten we carried to get 49. Write the 9 in the hundreds place of the product and the 4 in the thousands place.  
The second partial product is 4960. Add the partial products. 
The product is $\mathrm{5,394}.$
Try It 1.91
Multiply: $43(78).$
Try It 1.92
Multiply: $64(59).$
Example 1.47
Multiply:
 ⓐ $47\xb710$
 ⓑ $47\xb7100.$
Solution
ⓐ $47\xb710$.  $\begin{array}{c}\hfill 47\phantom{\rule{0.1em}{0ex}}\\ \hfill \underset{\text{\_\_\_}}{\times 10}\\ \hfill 00\\ \hfill \underset{\text{\_\_\_}}{470}\\ \hfill 470\end{array}$ 
ⓑ $47\xb7100$  $\begin{array}{c}\hfill 47\phantom{\rule{0.2em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\times 100}\phantom{\rule{0.2em}{0ex}}\\ \hfill 00\phantom{\rule{0.3em}{0ex}}\\ \hfill \underset{\text{\_\_\_\_\_}}{\begin{array}{c}\hfill 000\\ \hfill 4700\end{array}}\\ \hfill \mathrm{4,700}\phantom{\rule{0.2em}{0ex}}\end{array}$ 
When we multiplied $47$ times $10,$ the product was $470.$ Notice that $10$ has one zero, and we put one zero after $47$ to get the product. When we multiplied $47$ times $100,$ the product was $\mathrm{4,700}.$ Notice that $100$ has two zeros and we put two zeros after $47$ to get the product.
Do you see the pattern? If we multiplied $47$ times $\mathrm{10,000},$ which has four zeros, we would put four zeros after $47$ to get the product $\mathrm{470,000}.$
Try It 1.93
Multiply:
 ⓐ $54\xb710$
 ⓑ $54\xb7100.$
Try It 1.94
Multiply:
 ⓐ $75\xb710$
 ⓑ $75\xb7100.$
Example 1.48
Multiply: $(354)(438).$
Solution
There are three digits in the factors so there will be $3$ partial products. We do not have to write the $0$ as a placeholder as long as we write each partial product in the correct place.
Try It 1.95
Multiply: $(265)(483).$
Try It 1.96
Multiply: $(823)(794).$
Example 1.49
Multiply: $(896)201.$
Solution
There should be $3$ partial products. The second partial product will be the result of multiplying $896$ by $0.$
Notice that the second partial product of all zeros doesn’t really affect the result. We can place a zero as a placeholder in the tens place and then proceed directly to multiplying by the $2$ in the hundreds place, as shown.
Multiply by $10,$ but insert only one zero as a placeholder in the tens place. Multiply by $200,$ putting the $2$ from the $12.$ $2\xb76=12$ in the hundreds place.
Try It 1.97
Multiply: $(718)509.$
Try It 1.98
Multiply: $(627)804.$
When there are three or more factors, we multiply the first two and then multiply their product by the next factor. For example:
to multiply  $8\cdot 3\cdot 2$ 
first multiply $8\cdot 3$  $24\cdot 2$ 
then multiply $24\cdot 2$.  $48$ 
Translate Word Phrases to Math Notation
Earlier in this section, we translated math notation into words. Now we’ll reverse the process and translate word phrases into math notation. Some of the words that indicate multiplication are given in Table 1.5.
Operation  Word Phrase  Example  Expression 

Multiplication  times product twice 
$3$ times $8$ the product of $3$ and $8$ twice $4$ 
$3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}8,3\xb78,(3)(8),$ $(3)8,\phantom{\rule{0.2em}{0ex}}\text{or}\phantom{\rule{0.2em}{0ex}}3(8)$ $2\xb74$ 
Example 1.50
Translate and simplify: the product of $12$ and $27.$
Solution
The word product tells us to multiply. The words of $12$ and $27$ tell us the two factors.
the product of 12 and 27  
Translate.  $12\cdot 27$ 
Multiply.  $324$ 
Try It 1.99
Translate and simplify the product of $13$ and $28.$
Try It 1.100
Translate and simplify the product of $47$ and $14.$
Example 1.51
Translate and simplify: twice two hundred eleven.
Solution
The word twice tells us to multiply by $2.$
twice two hundred eleven  
Translate.  2(211) 
Multiply.  422 
Try It 1.101
Translate and simplify: twice one hundred sixtyseven.
Try It 1.102
Translate and simplify: twice two hundred fiftyeight.
Multiply Whole Numbers in Applications
We will use the same strategy we used previously to solve applications of multiplication. First, we need to determine what we are looking for. Then we write a phrase that gives the information to find it. We then translate the phrase into math notation and simplify to get the answer. Finally, we write a sentence to answer the question.
Example 1.52
Humberto bought $4$ sheets of stamps. Each sheet had $20$ stamps. How many stamps did Humberto buy?
Solution
We are asked to find the total number of stamps.
Write a phrase for the total.  the product of 4 and 20 
Translate to math notation.  $4\cdot 20$ 
Multiply.  
Write a sentence to answer the question.  Humberto bought 80 stamps. 
Try It 1.103
Valia donated water for the snack bar at her son’s baseball game. She brought $6$ cases of water bottles. Each case had $24$ water bottles. How many water bottles did Valia donate?
Try It 1.104
Vanessa brought $8$ packs of hot dogs to a family reunion. Each pack has $10$ hot dogs. How many hot dogs did Vanessa bring?
Example 1.53
When Rena cooks rice, she uses twice as much water as rice. How much water does she need to cook $4$ cups of rice?
Solution
We are asked to find how much water Rena needs.
Write as a phrase.  twice as much as 4 cups 
Translate to math notation.  $2\cdot 4$ 
Multiply to simplify.  8 
Write a sentence to answer the question.  Rena needs 8 cups of water for cups of rice. 
Try It 1.105
Erin is planning her flower garden. She wants to plant twice as many dahlias as sunflowers. If she plants 14 sunflowers, how many dahlias does she need?
Try It 1.106
A college choir has twice as many women as men. There are 18 men in the choir. How many women are in the choir?
Example 1.54
Van is planning to build a patio. He will have $8$ rows of tiles, with $14$ tiles in each row. How many tiles does he need for the patio?
Solution
We are asked to find the total number of tiles.
Write a phrase.  the product of 8 and 14 
Translate to math notation.  $8\cdot 14$ 
Multiply to simplify.  $\begin{array}{c}\phantom{\rule{2em}{0ex}}\\ \phantom{\rule{0.38em}{0ex}}\stackrel{3}{1}4\hfill \\ \phantom{\rule{0.1em}{0ex}}\underset{\text{\_\_\_}}{\times 8}\hfill \\ 112\hfill \end{array}$ 
Write a sentence to answer the question.  Van needs 112 tiles for his patio. 
Try It 1.107
Jane is tiling her living room floor. She will need 16 rows of tile, with 20 tiles in each row. How many tiles does she need for the living room floor?
Try It 1.108
Yousef is putting shingles on his garage roof. He will need 24 rows of shingles, with 45 shingles in each row. How many shingles does he need for the garage roof?
If we want to know the size of a wall that needs to be painted or a floor that needs to be carpeted, we will need to find its area. The area is a measure of the amount of surface that is covered by the shape. Area is measured in square units. We often use square inches, square feet, square centimeters, or square miles to measure area. A square centimeter is a square that is one centimeter (cm.) on a side. A square inch is a square that is one inch on each side, and so on.
For a rectangular figure, the area is the product of the length and the width. Figure 1.12 shows a rectangular rug with a length of $2$ feet and a width of $3$ feet. Each square is $1$ foot wide by $1$ foot long, or $1$ square foot. The rug is made of $6$ squares. The area of the rug is $6$ square feet.
Example 1.55
Jen’s kitchen ceiling is a rectangle that measures 9 feet long by 12 feet wide. What is the area of Jen’s kitchen ceiling?
Solution
We are asked to find the area of the kitchen ceiling.
Write a phrase for the area.  the product of 9 and 12 
Translate to math notation.  $9\cdot 12$ 
Multiply.  $\begin{array}{c}\phantom{\rule{2em}{0ex}}\\ \phantom{\rule{0.5em}{0ex}}\stackrel{1}{1}2\hfill \\ \phantom{\rule{0.1em}{0ex}}\underset{\text{\_\_\_}}{\times 9}\hfill \\ 108\hfill \end{array}$ 
Answer with a sentence.  The area of Jen's kitchen ceiling is 108 square feet. 
Try It 1.109
Zoila bought a rectangular rug. The rug is 8 feet long by 5 feet wide. What is the area of the rug?
Try It 1.110
Rene’s driveway is a rectangle 45 feet long by 20 feet wide. What is the area of the driveway?
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Section 1.4 Exercises
Practice Makes Perfect
Use Multiplication Notation
In the following exercises, translate from math notation to words.
$8\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}6$
$3\xb79$
$(20)(15)$
$39(64)$
Model Multiplication of Whole Numbers
In the following exercises, model the multiplication.
$4\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}5$
$3\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}9$
Multiply Whole Numbers
In the following exercises, fill in the missing values in each chart.
In the following exercises, multiply.
$0\xb741$
$(77)0$
$1\xb734$
$(65)1$
$1(\mathrm{189,206})$
 ⓐ $8\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}9$
 ⓑ $9\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}8$
$(58)(4)$
$638\xb75$
$\mathrm{9,143}\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}3$
$37(45)$
$89\xb756$
$53\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}98$
$19\xb710$
$(100)(25)$
$\mathrm{1,000}(46)$
$30\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}\mathrm{1,000,000}$
$156\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}328$
$472(855)$
$968\xb7926$
$(103)(497)$
$485(602)$
$\mathrm{3,581}\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}724$
Translate Word Phrases to Math Notation
In the following exercises, translate and simplify.
the product of $15$ and $22$
fortyeight times seventyone
twice $589$
ten times two hundred fiftyfive
Mixed Practice
In the following exercises, simplify.
$86\phantom{\rule{0.2em}{0ex}}\times \phantom{\rule{0.2em}{0ex}}29$
$341285$
$\mathrm{3,816}+\mathrm{8,184}$
$(77)(801)$
$947+0$
$\mathrm{15,382}\xb71$
In the following exercises, translate and simplify.
the difference of 90 and 66
twice 140
65 more than 325
the product of 15 and 905
subtract 45 from 99
the sum of 6,308 and 724
388 less than 925
Multiply Whole Numbers in Applications
In the following exercises, solve.
Party supplies Tim brought 9 sixpacks of soda to a club party. How many cans of soda did Tim bring?
Sewing Kanisha is making a quilt. She bought 6 cards of buttons. Each card had four buttons on it. How many buttons did Kanisha buy?
Field trip Seven school busses let off their students in front of a museum in Washington, DC. Each school bus had 44 students. How many students were there?
Gardening Kathryn bought 8 flats of impatiens for her flower bed. Each flat has 24 flowers. How many flowers did Kathryn buy?
Charity Rey donated 15 twelvepacks of tshirts to a homeless shelter. How many tshirts did he donate?
School There are 28 classrooms at Anna C. Scott elementary school. Each classroom has 26 student desks. What is the total number of student desks?
Recipe Stephanie is making punch for a party. The recipe calls for twice as much fruit juice as club soda. If she uses 10 cups of club soda, how much fruit juice should she use?
Gardening Hiroko is putting in a vegetable garden. He wants to have twice as many lettuce plants as tomato plants. If he buys 12 tomato plants, how many lettuce plants should he get?
Government The United States Senate has twice as many senators as there are states in the United States. There are 50 states. How many senators are there in the United States Senate?
Recipe Andrea is making potato salad for a buffet luncheon. The recipe says the number of servings of potato salad will be twice the number of pounds of potatoes. If she buys 30 pounds of potatoes, how many servings of potato salad will there be?
Painting Jane is painting one wall of her living room. The wall is rectangular, 13 feet wide by 9 feet high. What is the area of the wall?
Home décor Shawnte bought a rug for the hall of her apartment. The rug is 3 feet wide by 18 feet long. What is the area of the rug?
Room size The meeting room in a senior center is rectangular, with length 42 feet and width 34 feet. What is the area of the meeting room?
Gardening June has a vegetable garden in her yard. The garden is rectangular, with length 23 feet and width 28 feet. What is the area of the garden?
NCAA basketball According to NCAA regulations, the dimensions of a rectangular basketball court must be 94 feet by 50 feet. What is the area of the basketball court?
NCAA football According to NCAA regulations, the dimensions of a rectangular football field must be 360 feet by 160 feet. What is the area of the football field?
Everyday Math
Stock market Javier owns 300 shares of stock in one company. On Tuesday, the stock price rose $\text{\$}12$ per share. How much money did Javier’s portfolio gain?
Salary Carlton got a $\text{\$}200$ raise in each paycheck. He gets paid 24 times a year. How much higher is his new annual salary?
Writing Exercises
How confident do you feel about your knowledge of the multiplication facts? If you are not fully confident, what will you do to improve your skills?
How have you used models to help you learn the multiplication facts?
Self Check
ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.
ⓑ On a scale of 1–10, how would you rate your mastery of this section in light of your responses on the checklist? How can you improve this?