Let's take a look at the area model below.

We complete this area model by finding the areas of each small rectangle and writing these values on the diagram:

  • Let's first look at the blue rectangle (the one on the top left). Its length is 10, and its width is 10. Therefore, the area of this rectangle must be 10 \times 10 = {\color{blue}100}. Let's add this to our model:

  • Now, let's look at the pink rectangle (the one on the top right). Its length is 2, and its width is 10. Therefore, the area of this rectangle must be \begin{align} 2 \times 10 &= {\color{blue}20}. \end{align} Let's add this value to our model:

  • Filling the other two missing values in the same way, we get the following:

And we're done!

FLAG

From left to right, find the missing numbers in the area model below.

EXPLANATION

We need to look at the blue and pink rectangles:

  • Let's first look at the blue rectangle on the top left. Its length is 80, and its width is 40. Therefore, the area of this rectangle must be 80 \times 40 = {\color{blue}3,200}. Let's add this to our model:

  • Now, let's look at the pink rectangle (the one on the top right). Its length is 2, and its width is 40. Therefore, the area of this rectangle must be 2 \times 40 = {\color{blue}80}. Let's add this to our model:

Therefore, from left to right, the missing numbers are 3,200 and 80.

FLAG

Find the missing number in the area model above.

a
$110$
b
$900$
c
$1,800$
d
$180$
e
$1,500$

From left to right, find the missing numbers in the area model above.

a
$40$ and $350$
b
$35$ and $270$
c
$20$ and $350$
d
$40$ and $270$
e
$20$ and $270$

We can use area models to represent two-digit by two-digit multiplication problems.

For example, let's consider the following area model:

Now, let's look at the big rectangle:

  • its length is 10+2=12

  • its width is 10+5=15

  • its area is 100 + 20 + 50 + 10 = 180

Therefore, this area model can be used to represent the following multiplication problem:

12 \times 15 = 180

FLAG

The area model above can be used to represent the following multiplication problem:

39 \times 23 = \fbox{[math]\phantom{00}[/math]}

What is the missing number?

EXPLANATION

Let's look at the big rectangle:

  • its length is 30+9=39

  • its width is 20+3=23

  • its area is 600 + 180 + 90 + 27 = 897

Hence, this area model can be used to represent the following multiplication problem:

39 \times 23= \fbox{897}

Therefore, the missing number is 897.

FLAG

The area model above can be used to represent the following multiplication problem:

\[ 29 \times \fbox{$\phantom{00}$} = 2,407. \]

What is the missing number?

a
$77$
b
$38$
c
$29$
d
$83$
e
$803$

The area model above can be used to represent the following multiplication problem:

\[ \fbox{$\phantom{00}$} \times 54 =1,566. \]

What is the missing number?

a
$29$
b
$19$
c
$34$
d
$24$
e
$39$

Using the area model below, find the value of 32 \times 45.

EXPLANATION

First, we compute the missing values. This gives the following picture:

Now, notice the following regarding the big rectangle:

  • its length is 30+2=32

  • its width is 40+5=45

  • its area is 1,200 + 80 + 150 + 10 = 1,440

Therefore, this area model can be used to represent the following multiplication problem:

32 \times 45 = 1,440

FLAG

Using the area model above, find the value of $32 \times 26.$

a
$792$
b
$902$
c
$832$
d
$612$
e
$652$

Using the area model above, find the value of $65 \times 27.$

a
$1,345$
b
$1,755$
c
$1,545$
d
$1,845$
e
$1,575$

Using the area model below, find the value of 97 \times 51.

EXPLANATION

First, we set up the model. The numbers 97 and 51 can be expressed in expanded form as {\color{blue}90}+{\color{blue}7} and {\color{red}50}+{\color{red}1}. So, we place {\color{blue}90} and {\color{blue}7} above the rectangles and {\color{red}50} and {\color{red}1} to the left of the rectangles.

Next, we compute the missing values. This gives the following picture:

Now, notice the following regarding the big rectangle:

  • its length is 90+7=97

  • its width is 50+1=51

  • its area is 4,500 + 350 + 90 + 7 = 4,947

Therefore, this area model can be used to represent the following multiplication problem:

97 \times 51 = 4,947

FLAG

Using the area model above, find the value of $17 \times 14.$

a
$238$
b
$278$
c
$198$
d
$268$
e
$228$

The area model below represents the multiplication problem $42 \times 56.$ Insert the missing numbers.

a
b
c
d
e
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