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Browse Middle School Negative Numbers
Stars indicate particularly interesting answers or good places to begin browsing.

Selected answers to common questions:
    Inequalities and negative numbers.
    Positive/negative integer rules.

Raising Both Sides of an Inequality to a Power [06/19/2006]
You have to flip the sign in an inequality if you multiply both sides by a negative number. Is there any rule that says when you have to flip the sign if you raise both sides to a power?

Reversing the Inequality, Explained to a Student with Scale and Number Line Analogies [09/21/1998]
Why does the inequality sign reverse when you multiply by a negative number?

Reversing the Inequality, Explained to a Teacher with an Antigravity Metaphor [03/09/1999]
Why do we reverse the inequality symbol when dividing/multiplying by a negative number?

Solving x-(-16) = 0 [02/17/1998]
How do you solve: x- -16 = -16?

Solving -X = 3 [10/26/1998]
How do you solve -X = 3? How can a negative equal a positive?

Spaces and the Number Line [02/26/2003]
If you say, 'How many degrees are there between -2 and 4?' would you count the 0 degrees and answer 7 degrees or would you not count the nought and answer 6 degrees?

Square Root of 64 [6/20/1996]
I would like to know the square root of 64.

Square Root of a Negative Number Squared [01/23/1997]
Is Sqrt(-6)^2 equal to 6 or -6?

Subtracting and Borrowing in a Column [09/05/2002]
A student borrowed in a column as follows: 6.9 - 7.92, to get -2.98. Why won't borrowing work with this number?

Subtracting as Adding a Negative [01/14/2002]
My teacher says to think of the question as a negative number, not a minus number, but I don't know how he's doing that.

Subtracting Negative Integers [09/12/2001]
I have questions like: -3 - -13. My teacher said to do it in a money way....

Subtracting Negative Numbers [05/11/1998]
Can you explain how to subtract a negative number from a positive number and a positive number from a negative number?

"Subtraction" and "Negative"--Same Sign, Different Concepts? [12/14/2005]
Why do we use "-" to mean both "subtraction" and "negative", when those are two different concepts?

Talking About Zero, Absolute Zero and Negative Numbers [11/12/2003]
Are there any useful strategies other than temperature to introduce negative numbers, and also to teach about zero, its properties, and how they differ from those of absolute zero?

Understanding Negative Numbers [5/18/1996]
I don't understand negatives - can you help me?

Using Cancellation to Add Positives and Negatives [10/27/2003]
How can I memorize the rules for adding positives and negatives?

What If There Was No Zero? [10/21/2003]
Why did it take so long to discover zero? Why did early civilizations not need zero? How would math as we know it be different if there was no zero?

What is an Integer? [10/03/2002]
Why isn't -1/2 considered an integer?

What Sign Do You Use? [10/21/2001]
If two negatives equal a positive, then how do you do it, and what sign do you take?

When Do You Flip an Inequality Sign? [12/19/2005]
What does it mean to change the sense of an inequality? When do you have to do that?

Why a Negative x Negative = Positive [11/4/1996]
A teacher in a course I took last fall challenged us to come up with a way to demonstrate or prove how it is that a negative times a negative equals a positive (how to explain this). The only thing I could come up with is that it is positive because one is negating a negative.

Why Aren't There Negative Prime Numbers? [12/10/1999]
Why can't negative numbers be prime numbers?

Why Does a Negative Times a Negative Equal a Positive? [03/01/1998]
Using the distributive law to reason why a negative times a negative equals a positive.

Why Does a Negative Times a Negative Make a Positive? [11/25/2003]
Why is a negative times a negative a positive? When you answered this question to other people, the way you explained it was over my head. Can you help me understand this?

Why Do Two Negatives Equal a Positive? [6/6/1996]
I don't understand why two (-) = the +.

Why Do We Learn about Negative Numbers? [10/14/2004]
Why do we have to learn about negative numbers? The only context where I can see it being useful is in determining temperature.

Why Flip the Inequality Sign? [10/26/2001]
Please tell me why you flip the inequality sign when dividing by a negative number.

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