Negative numbers and absolute value : Khan Academy on a Stick

Khan Academy on a Stick

Arithmetic

Negative numbers introduction
Mysterious negative numbers! What ARE they? They are numbers less than zero. If you understand the nature of below zero temperatures, you can understand negative numbers. We'll help.
Negative numbers and number line examples
Given a few negative numbers on a number line, let's see if we can determine what negative numbers are elsewhere on the number line.
Ordering negative numbers
Is -40 bigger than -10? When ordering negative numbers from least to greatest, careful that you don't get hung up on the "amount" of the number. Think about what that negative sign really means!

Negative number basics

What is a "negative number"? What happens when I add or subtract one of these? If you come to this tutorial armed with the basics of adding and subtracting numbers, you'll learn about what happens in the world below zero! You will learn what negative numbers are and how we can add and subtract them.

Adding negative numbers
Using number lines and an understanding of absolute values, we walk you through the exercise of adding negative numbers.
Adding numbers with different signs
Let's a take stab at adding numbers with both positive and negative signs. Using a number line makes this exercise easier and we recommend it.
Learn how to add and subtract negative numbers
Let's practice adding and subtracting both positive and negative numbers. Remember that two negatives make a positive, or another way of looking at, subtracting a negative is the same as adding.
Subtracting a negative = adding a positive
Logic tells us (as does this video) that subtracting a negative number is the same thing as adding the absolute value of that number. Watch and be amazed.
Negative number word problem
Let's challenge ourselves with a word problem that requires us to plot points, positive and negative, and find the difference.
Rational number word problem with decimals
Your checking account is overdrawn. Not good. Use your knowledge of decimals and adding negative and positive numbers to bring your account back into the black.
Adding/subtracting negative numbers
Adding and subtracting negative numbers

Adding and subtracting negative numbers

You understand that negative numbers represent how far we are "below zero". Now you are ready to add and subtract them! In this tutorial, we will explain, give examples, and give practice adding and subtracting negative numbers. This is a super-important concept for the rest of your mathematical career so, no pressure, learn it as well as you can!

Multiplying positive and negative numbers
Here we explain some rules of thumb regarding the multiplication of positive and negative numbers.
Why a negative times a negative is a positive
Why are the products of negative numbers defined in the way they are? We'll use the distributive property to help you with your understanding.
Why a negative times a negative makes intuitive sense
We use the repeated addition model of multiplication to give an intuitive understanding of multiplying negative numbers.
Dividing positive and negative numbers
In this video we take you through the basics of dividing with negative numbers. You'll need to draw from your multiplication skills, too.
Multiplying numbers with different signs
Help us find the product of numbers with different signs.
Multiplying and dividing negative numbers
Multiplying and dividing negative numbers

Multiplying and dividing negative numbers

It is starting to dawn on you that negative numbers are incredibly awesome. So awesome that you are feeling embarrassed to think how excited you are about them! Well, the journey is just beginning. In this tutorial we will think about multiplying and dividing numbers throughout the number line!

Absolute value and number lines
One easy way to think of absolute value is the distance it is from zero. To do that, a number line comes in handy. Watch and learn.
Absolute value smallest to biggest
Not only will we identify several absolute values in this example, but we will order them from smallest to largest. Content provided by The NROC Project - ©Monterey Institute for Technology and Education
Absolute value of integers
Let's mix a little algebra into our discussion of absolute value. What if we are looking for the |x|? If we know what x equals, we can do it. Follow along.
Comparing absolute values
When we compare numbers we use the concepts of greater than (>), less than (<), and equal to (=). The same is true of absolute values.
Absolute value word problems
Here are a few word problems that ask us to apply our new absolute value knowledge. As with all word problems, read them a couple of times before jumping to an answer.
Constructing and interpreting absolute value
Watch as we apply our understanding of absolute value and adding/subtracting negative numbers to solve some word problems.

Absolute value

You'll find absolute value absolutely straightforward--it is just the "distance from zero." If you have a positive number, it is its own absolute value. If you have a negative number, just make it positive to get the absolute value. As you'll see as you develop mathematically, this idea will eventually extend to more contexts and dimensions, so it's super important that you understand this core concept now.