Rules for Multiplying Positive and Negative Numbers

Rules: (+) (+) = (+)

(+) (-) = (-)

(-) (+) = (-)

(-) (-) = (+)

To help remember these rules:

Use a VCR to help visualize the motion of an individual.

Let the positive sign represent forward motion.

Let the negative sign represent reverse motion.

Let the first factor represent the motion of the person in a videotape.

Let the second factor represent the motion of the VCR.

So, if a person is walking forward (+), and the VCR is running in forward (+), then the person appears

to be walking in a forward direction (+).

If a person is walking forward (+), and the VCR is running in reverse (-), then the person appears

to be walking in a backwards direction (-).

If a person is walking backwards (-), and the VCR is running in forward (+), then the person appears

to be walking in a reverse direction (-).

If a person is walking backwards (-), and the VCR is running in reverse (-), then the person appears

to be walking in a forward direction (+).

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Another way to remember these rules:

Let the positive sign represent good events and good people.

Let the negative sign represent bad events and bad people.

Let the first factor represent an event.

Let the second factor represent the person.

So, if good things (+) happen to good people (+), that’s good (+).

If bad things (-) happen to good people (+), that’s bad (-).

If good things (+) happen to bad people (-), that’s bad (-).

If bad things (-) happen to bad people (-), that’s good (+).

Sorry! That last example is not good Christian theology!

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Vicki Calkins shared the following way of remembering these rules:

a good guy = +
a bad guy = -
 
coming into town = +
going out of town = -
 
when a good guy (+) comes into town (+) that's good (+)
when a good guy (+) leaves town(-) that's bad (-)
when a bad guy (-) comes into town (+) that's bad (-)
when a bad guy (-) leaves town (-) that's good (+)