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Why Zero is neither Positive nor Negative


Date: 10/5/95 at 22:5:27
From: Anonymous
Subject: Is 0 a negative or a positive?

Dear Dr. Math,

   My class and I are wondering if 0 is a negative or a positive 
number and why.  My name is David and I am in fifth grade at 
Kyrene De La Sierra in Phoenix.

				Sincerely,
                          Ms. Kieselbach's class


Date: 10/6/95 at 16:16:32
From: Doctor Ken
Subject: Re: Is 0 a negative or a positive?

Hello!

Actually, zero is neither a negative or a positive number.  The 
whole idea of positive and negative is defined in terms of zero.  
Negative numbers are numbers that are smaller than zero, and 
positive numbers are numbers that are bigger than zero.  Since 
zero isn't bigger or smaller than itself (just like you're not 
older than yourself, or taller than yourself), zero is neither 
positive nor negative.

People sometimes talk about the "non-negative" numbers, and what 
that means is all the numbers that aren't negative, in other words 
all the positive numbers and zero.  So the only difference between 
the set of positive numbers and the set of non-negative numbers is 
that zero isn't in the first set, but it is in the second.  
Similarly, the "non-positive" numbers are the negative numbers 
together with zero.

-Doctor Ken,  The Geometry Forum

    
Associated Topics:
Elementary Number Sense/About Numbers

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