Adding Positive and Negative Numbers

A foundational skill for any preAlgebra student is to be confident adding positive and negative numbers. GradeA will help you gain your confidence by teaching you to truly understand the concept behind adding and subtracting numbers. After this lesson, not only will you know how to do it, it will also make sense.

Setting the Foundation: Teaching Adding withMoney

In our demonstration we are going to use two different types of money.

  1. The first kind is going to be normal dollar bills like the one below.
  2. The second kind is something called "debt" slips. Think of it as money that you borrowed from a friend. If you have a one dollar debt slip that means that you owe a fried one dollar.
One Dollar Bill  

Now, all we have to do it determine how many dollars we have in our bank account - or our piggy bank.

Makes sense, right?

Determing Positive vs. Negative
  1. Positive numbers (+) will be our regular dollar bills. Remember, if a number has no sign in front of it, it is positive.
  2. Negative numbers (-) will be the debt slips.

Determing when to Add and when to Subtract
  1. We will always add the first number to the bank - whether it is dollar bills or debt slips - we always put the first one in the back. After that...
  2. When we see a addition sign (+) we are going to add the next number (either dollar bills or debt slips) to our bank.
  3. When we see a subtraction sign (-) we are going to remove the next number (either dollar bills or debt slips) from our bank.

*TIP: Do not get confused between a negative sign and a subtraction sign. They both mean the same thing.

A dash (-) can be used as either, but just use it once! Two dashes in a row (- -) really means to add!

Just remember this: "A dash is a dash!"


Adding Positive and Negative Number Examples

Here are a few practice problems to try. The answers are shown below. Give them a try, and then check your answers - no peaking!

Example #1:     5+3 = ?

Example #2 :  -5+3 = ?

Example #3 :   5-3 = ?

Example #4:     5+-3 = ?

Example #5 :   5--3 = ?


Answers:  1) 8        2) -2        3) 2        4) 2        5) 8

Hopefully GradeA has helped you gain some confidence in adding and subtracting. We know that positive and negative numbers can get confusing, but it is important to learn them now becase you will use them so often.

Return from adding positive and negative numbers to preAlgebra help.



Untitled Document

Stay connected


HomeSite SearchMath Help BlogHelp Keep GradeA Free

Written by Team, all rights reserved.