Math Adventures/Multiplying Negative Numbers

In mathematics, multiplying two negative numbers together gives a positive number as a result. For example, -2 x -5 = 10. For many people, this seems strange.

Provide a list of everyday examples that illustrate the multiplication of two negative quantities to produce a positive result.

What can you add to this list of possible answers:

1. Each source of pollution contributes to degrading our environment. The more pollution sources we remove, the greater impact there is on the environment. Removing (a negative) pollutants (an environmental negative) provides a better environment (a positive).
2. Turning around and then walking backwards results in forward progress.
3. When played backwards, a video originally recording a water tank draining now shows a tank filling.
4. Bank assets increase as each debt is discharged. Each debt (negative) removed (negative) from an account balance result in positive financial standing.
5. Public safety increases as each criminal is quarantined.
6. Each instance of scrubbing (removing dirt, a negative) on a dirty (negative) surface leaves the surface cleaner (a positive result).
7. Reducing each instance of a bad habit (like smoking) removes negative health impacts, resulting in positive health benefits.
8. Each incorrect answer removed (corrected) from a test improves the accuracy of the test (a positive outcome).