Multiplication as Repeated Subtraction

Multiplication as Repeated Subtraction

by Sarah Fox

​Remember:

​Subtracting integers sometimes requires us to add zero pairs (+ and -) in order to take away the right amount. (Throwing them in the garbage can.)

​

​The image on the right would have a value of 8 after we subtract the two negatives.

Multiple Choice

4 - (-6)

• -10

• 10

• -2

• 2

Multiple Choice

4 - 6

• 10

• -10

• 2

• -2

Multiple Choice

-4 - 6

• -10

• 10

• 2

• -2

Multiple Choice

-4 - (-6)

• 10

• -10

• 2

• -2

​Multiplying Integers Review

​Remember that multiplying is telling you how many groups there are.

​

​Ex. 2(-4) is 2 groups of -4 which equals -8

​

​Keep in mind that the negative (-) also means opposite.

​

​Ex. -2(-4) is the OPPOSITE of 2(-4) so it equals 8 <--- Not negative!

Multiple Choice

3(-5)

• -15

• 15

• 2

• -2

Multiple Choice

-3(-5)

• -15

• 15

• 2

• -2

Multiple Choice

-3(5)

• -15

• 15

• 2

• -2

Multiple Choice

3(5)

• -15

• 15

• 2

• -2

Open Ended

How can you tell if the answer will be positive or negative when you multiply?

​Repeated Subtraction

​Sometimes we subtract the same thing a lot!

​

​Ex. 10 - (-2) - (-2) - (-2)

​

​Could be written in a simpler form using Multiplication.

​

​10 - 3(-2)

​

​Since we are subtracting 3 groups of -2.

Multiple Choice

5 - 3 - 3 - 3 - 3 - 3

• 5 - 5(-3)

• 5 - 5(3)

Multiple Choice

-7 - (-4) - (-4)

• -7 - 2(-4)

• -7 - 2(4)

Poll

5 - 4(-2)

• 5 - (-2) - (-2) - (-2) - (-2)

• 5 - 2 - 2 -2 -2

Multiple Choice

8 - 3(4)

• 8 - (-4) - (-4) - (-4)

• 8 - 4 - 4 - 4

Fill in the Blanks

Write -6 - 5 - 5 - 5 - 5 as multiplication.