# Re: [xmca] a minus times a plus

Hello folks. You're inspiring this lurker to post. Here's how I, another literacy person, learned it.
```
Good guy = + (positive)
Coming to town = +
Leaving town = -

Good guy comes to town (+*+) = +
Good guy leaves town (+*-) = -
Bad guy comes to town (-*+) = -
Bad guy leaves town (- * -)= +

```
Add a background scenario of the stereotype of the old West in America, and you have the whole picture. I guess this is just a narrative around the "leave it alone/reflect it through a mirror" pattern Jerry Balzano spoke about. I found a narrative like this really helped my 12 year old former students get this pattern. . .
```
Linda Williams

Linda Williams, Ph.D.
Assistant Professor
College of Education
Department of Teacher Education
313C Porter Hall
Eastern Michigan University
Ypsilanti, MI 48197
734-487-7120 , Ext. 2635
Fax:  734-487-2101

lwilli55@emich.edu

On Apr 27, 2009, at 11:53 PM, Duvall, Emily wrote:

```
```My non-math vision.
If I multiply a positive number by 0, I still have 0.
If I multiply a positive number by less than 0, a negative number, I
```
will still have less than 0... only it will be a more specific amount of
```less than zero.
```
Ergo multiply a positive number by a negative number and it will have to
```be a negative result.
~em

-----Original Message-----
From: xmca-bounces@weber.ucsd.edu [mailto:xmca-bounces@weber.ucsd.edu]
On Behalf Of Mike Cole
Sent: Monday, April 27, 2009 3:48 PM
To: eXtended Mind, Culture, Activity
Subject: [xmca] a minus times a plus

```
Since we have some mathematically literate folks on xmca, could someone
```please post an explanation of why

multiplying a negative number by a positive numbers yields a negative
number? What I would really love is an explanation
that is representable in a manner understandable to old college
professors
and young high school students alike.

mike
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```
```

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```