One of my first tasks as a software intern, was to write code-analysis rules to help prevent the Y2K disaster. (Yes interns can do great things… OR, y2k was never meant to be taken seriously)

One tidbit I learned was that Leap Years:

• do happen every 4 years 
• but not every 100 years
• but do happen every 400 years

Simple! Also, you could just click here.