Adding Integers

Hello all,
Just wanted to post a quick review for your assessment Tuesday. We'll be checking the practice quiz Monday so please remember to bring it with you to class for workshop.

On this assessment, we'll be covering 8-1 through 8-3 (adding/subtracting integers). For subtraction, please review the previous post about the KFC method. Remember, Keep, Flip, Change!!! :)

For addition:

First, remember that a negative plus a negative will always equal a negative. If you lose five bucks and then you lose three more, you've LOST a total of 8 bucks, and a loss is represented by a negative, so you'd have -8 dollars.

-5 + -3 = -8

The tricky part comes in when you need to add a negative and a positive together.

Let's review the 3 methods we can use to add negative and positive integers:

1. Use a number line. From your starting point, move to the right if adding a positive integer; move to the left if adding a negative integer.

2. Use the method you have in your notes:
     1. Ignore the signs. What numbers do you have?
     2. Find the difference of those two numbers.
     3. For your answer, keep the sign of the biggest number.
     
     -7 + 4 -----> What numbers do I have if I ignore the signs? 7 and 4.
       7 - 4 ----->  Now, I take the difference of the two numbers.
       = 3   -----> Since the number with the greatest absolute value was -7, the answer becomes negative.
       = - 3

3. Use counters! Place negative and positive symbols inside a shape of your choosing. Cancel out whatever you can. What you're left with is your answer. Example:

The following picture represents 4 + (-5):

Since 1 positive is cancelled out by one negative, we are left with this, which represents -1:

And voila! You have your answer :)

If you're having a hard time adding integers in your head, any of these 3 methods will help you out. Happy adding!