Views field filter handler
There are two ways to do this that come to mind:


Use Computed Fields: https://drupal.org/project/computed_field. I haven't personally used this module but I've seen it recommended a number of times. You could create a hidden field on each piece of content which computes the value you desire. Then this can be used in the view as easily as any other field for both display and filtering.
Use views_php field: https://drupal.org/project/views_php. This will show up in the view options as 'Global: PHP' and will allow you to do pretty much anything with your data that you want to. The authors caution it's use because it's pretty easy to mess things up. I've found it to be a quick solution to problems. (As a side note, the most recent release of this functions differently in what variables it allows you to access, so be careful if doing updates. I would suggest using the most recent version.) Your code could be as simple as this in the output box: 

&lt;?php
$new_value = $row-&gt;value_1 * $row-&gt;value_2;
print $new_value;
?&gt;


Then you could create a "Global: PHP" sort by with something like this:

$first = $row1-&gt;value_1 * $row1-&gt;value_2;
$second = $row2-&gt;value_1 * $row2-&gt;value_2;

if ($first &gt; $second) {
  return 1;
}elseif ($first &lt; $second){
  return -1;
}else{
  return 0;
}