Multiplying by Factors 11 to 19

Lesson 7

Multiplying
by Factors

11 to 19

7

6

5

12

10

9

8

18

14

13

11

4

3

2

1

17

16

15

Today we will…

Use the splitting strategy to multiply
two- digit factors by one-digit factors.

Here’s our problem

4 x 15 = _____

●I will use the splitting strategy to figure out

the product.

●I could split 15 several ways. For instance, I

could split it into 8 and 7, or I could split it into 4

and 11. But I choose to split it into 10 and 5.

●Why does splitting 15 into 10 and 5 make the

problem easier?

Why do we split into

10?

-Splitting 15 into 10 and 5 also splits it

into its place- value parts.

-The 1 is in the tens place. It has a

value of 10.

-The 5 is in the ones place. It has a

value of 5.

Multiplying 4 x 15

Now instead of 4

times 15, I have two
easier multiplication
problems to solve:
- 4 times 10 and 4

times 5. - Then, I can
add the products.

4 x 15 = ____
4 x 10 = 40
4 x 5 = 20

40 + 20= 60

4 x 15 = 60

Let’s Try Splitting

10

5

10

5

10

5

10

5

Where does the
10 come from?

Where does
the 5 come

from?

Using the Splitting

Strategy

15 x 6 = ____

-When I split 15 into 10 and 5, I have
two easier problems: 10 times 6 and

5 times 6.

15 x 6 = ____

10 x 6= 60
5 x 6 = 30

60 + 30 = 90

Where
does the
10 come

from?

Where

does the 5

come
from?

Using the Splitting Strategy

17 x 5 = ____

-How can we split 17 to make it easier

to multiply by 5?

________________

-Once we split 17 we can multiply
them by 5. What two equations

should I write? ______________

and _______________

What do we do now to find
the product of 17 times 5?

(Write the equation)

Let’s go to WorkSpace

Page 11

5 x 18

Independent Work Time!

Please work on WorkSpace page 12.