Have you taken a look at the Wikipedia entry for magic number?
It goes into a bit of detail about all of the ways the magic number reference is made. Here's a quote about magic number as a bad programming practice
The term magic number also refers to the bad programming practice of using numbers directly in source code without explanation. In most cases this makes programs harder to read, understand, and maintain. Although most guides make an exception for the numbers zero and one, it is a good idea to define all other numbers in code as named constants.
