Multiplication of Integers

Introduction

In this lesson, we will review the multiplication of integers. In order to multiply integers you must know the following key points:

Key Points:

• Integers are distributed in 2 categories: positives and negatives
• Integers are whole numbers
• Zero is neither a positive or negative number
• If the signs are the same the product will be positive
• If the signs are different the product will be negative 

 Figure 1 Multiplication of Integers Number Line

Multiplication of Integers

Let's say that we have the following problem:

4 x -8

From the above key points, we know that if the signs are different, then the product will be negative.
In this case we have positive 4 (+4) and negative 8 (-8). Since the signs are different we know that the product will be negative. Now just simply multiply 4 x 8 and we get a product of 32. Remember to add the negative sign to get your final product of -32.

4 x -8 = -32

Subtraction of Integers

Introduction

In our previous post we reviewed the addition of integers. Well, subtraction of integers is pretty much the same concept because you are still handing integers except this lesson will deal with subtraction.

Key Points:

• Integers are distributed in 2 categories: positives and negatives
• Integers are whole numbers
• Zero is neither a positive or negative number

 Figure 1 Subtraction of Integers Number Line

Subtraction of Integers

Let's say that we have the following problem:

-7 - 9

The above problem is telling us that we have -7 and we have go back 9 spaces like this:

So as you can see the point of doing -7-9 is to go back -9 spaces or 9 spaces back from the number -7 and so the answer is going to be -17.

I highly recommend to practice this and do so with number lines and later on you will get how to do it and you will easily know how to without the number line!