title: How is a 1s complement checksum useful for error detection?
body: <p>A checksum can be generated simply by adding bits. How is the extra step of taking the 1s complement useful?</p>
  
  <p>I understand the theory. I know how to calculate 1s complement and I know about how adding the complements makes the result all 1s.</p>
  
  <p>I would like to see a simple example of how an error is detected.</p>