Prealgebra Adding and Subtracting

More About Adding and Subtracting

Adding Integers in the Card Game

Red is negative and black it positive
Let's add some numbers together

The Goal is to get back to zero

Multiple Choice

This is Ariel's had what is the sum of her hand?

• 1

• 15

• 12345

• -15

Poll

If Ariel were to pick a black 4 what would that do to her answer?

• Make it more positive?

• Make it more negative

• It wouldn't make a difference

Multiple Choice

If Ariel were to pick a black 4 what would her hand now be?

• 5

• -5

• 4

• -4

Multiple Choice

If Herman picked red 2, red 3, black 4, black 5, and red 6 what does Herman need to pick to get back to 0?

• -2

• 2

• 6

• -6

Open Ended

How do you know what to add to Herman's hand to get him back to zero to win the game?

Poll

Bill and Ted are playing each other at the integer game who had the better hand?

• Bill

• Ted

• They tied

Multiple Choice

Bill and Ted are playing each other at the integer game. What is Bill's had equal?

• 10

• -37

• 37

• 1

Multiple Choice

What does Ted need to tie with Bill?

• -4

• 11

• 5

• -11

Let's dive deeper into Integers

• When subtracting integers the signs and placements are important

• They can sometimes mean we add numbers

• I know but how well if the signs are opposite we will add the numbers and the placement will tell us if the answer is negative or positive

Poll

What do you think if we have -1-2, would the answer be negative or positive?

• Negative

• Positive

Multiple Choice

What do you think the answer will 6-(-5)?

• Negative

• Positive

Multiple Choice

Solve -10-12

• -22

• 22

• 2

• -2

Multiple Choice

Solve 15-(-12)

• 3

• -3

• -27

• 27

Open Ended

What is happening in the previous 2 questions? Why do you think that happened?

Why did we add when it says to subtract?

When subtracting you are taking that number and its value away from the Minuend (the first number).

Real purpose of subtracting

• When you subtract a positive from a negative you are making it more negative

• i.e. -3-5=8

• When you subtract a negative from a positive you are making it more positive

• i.e. 15-(-13)=28
  

Multiple Select

Solve  $$-43-\left(-28\right)$$ . Why are you actually subtracing?

• -15

• -71

• 15

• The signs for both values are the same

• Your adding more negatives