Addy finds the area of a 5-inch by 17-inch rectangle by breaking it

into 2 smaller rectangles. Show one way that he could have

solved the problem. What is the area of the rectangle?

How can we find the area?

17 in.

​5 in.

We can decompose the rectangle!

Step 1 - cut the larger number into two numbers that are easier to multiply by.
Step 2 - multiply both new numbers by the number that stayed the same.
Step 3 - add the products together.

​5 in.

10 in.

7 in.

We can decompose the rectangle!

Step 1 - cut the larger number into two numbers that are easier to multiply by.
Step 2 - multiply both new numbers by the number that stayed the same.
Step 3 - add the products together.

​5 in.

10 in.

7 in.

​5 x 10 = 50
5 x 7 = 35
50 + 35 = 85 in. squ.

How can we find the area?

We can compose the shape!

Step 1 - Draw to complete the rectangle.
Step 2 - multiply rows by columns
Step 3 - subtract the number of blank/white pieces.

We can compose the shape!

Step 1 - Draw to complete the rectangle.
Step 2 - multiply rows by columns
Step 3 - subtract the number of blank/white pieces.

​4 x 4 = 16
16 - 4 = 12
12 units squ.

How can we find the are?

How can we find the are?

​5

​4

How can we find the are?

​5

​7

​9

​63

​4

How can we find the are?

​5

​7

​9

​63

​5

​4

​4

​20

How can we find the are?

​5

​7

​9

​63

​5

​4

​4

​20

​63 - 20 = 43 squ cm.

The next 4 questions are for you and your table