If you know how many years or months you got left until the retirement or any other event or project in your life, Excel can return you the exact date and the number of days left to reach it.
This well kept secret surfaced just recently. All Apple devices running iOS 7 have a pretty darn well hidden Easter egg. Just follow this step-by-step instructions carefully and the very first Mac OS version 1 will appear on your iPhone or iPad. How freaking awesome is that?