Subtracting Negatives

Topic:Arithmetic, Arithmetic Operations, Subtraction

We want to explore how to subtract negative numbers. Let's start by getting comfortable with basic subtraction. Using the applet below, try to subtract positive numbers of the form big - little.

How does this applet show basic subtraction working? Explain what is happening in your own words.

Now that we are comfortable with basic subtraction, let's look at subtractions of the form little - big. Use the applet below to investigate what happens if both sliders are positive, but the second is the larger of the two.

In general, when subtracting positive numbers of the form little - big, we subtract the numbers as usual, and then make the result negative. Explain how you see this process working in the applet.

Now, let's investigate something of the form negative - positive. Use the applet below to try and determine what happens in this case.

In general, when looking at problems of the form negative - positive, we subtract the two numbers as usual. Then the solution has the sign of the number with the largest magnitude.. Explain how you see this process working in the applet.

Let's look at things of the form positive - negative. Use the applet below to investigate this case.

In general, when looking at problems of the form positive - negative, we add the two numbers to get the result. Explain how you see this process working in the applet.

Finally, use the applet to investigate the case of negative - negative.

In general, when looking at problems of the form negative - negative, we use the fact that a double negative is a positive and change the problem to a negative + positive. Explain how you see this process working in the applet.

Subtracting Negatives

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