The virtual Easter egg has been around for more than three decades now. Coined -- as far as anyone can tell -- by Atari's Adventure, which was released in 1979, the virtual Easter egg is a hidden message or in-joke built into a computer program, icon, or video game. Apple has been playing along since the very beginning, building small Easter eggs into many of their most famous icons.

Earlier this week, Electricpig called attention to many of the secret messages hidden inside the icons, sparking a series of follow-up posts on other websites and blogs. But they got some things wrong -- "Lorem Ipsum Dolor Sit Amet Etiam" is not Latin for "Hello world! Etcetera," but rather a Latin-esque string of nonsense that's been used as a placeholder by designers and editors for years -- and guessed on others: Does the Find My iPhone app actually show the location of Steve Jobs' Manhattan apartment in the San Remo building?

Here, we pulled together nine Apple Easter eggs that were definitely added to the icons on purpose and one that has been a mystery for years:

Apple's calculator icon displays the number 12374218.75. In putting this story together, I spent a considerable amount of time looking for an explanation, a reason this number is the default. It must mean something, right? All of Apple's other dates and icons have been carefully chosen. At least a dozen forums and message boards pose the question, but none seem to point to a definitive answer. One discussion on the official Apple support forum dates back to September 11, 2006: "Curious minds want to know... what is the significance of Calculator's icon having 12374218.75 as the number?" Any idea?

Update: After this article posted, Redditors offered up a potential solution. Steve Wozniak appears to have confirmed that they got it right.