Have you been practicing the Day of the Week For Any Date feat? Here's a quick test: On what day of the week does September 6th, 2008 fall?

If you took the time to work through that, then you should have come up with Saturday. Those of you who have performed this for friends, family or even total strangers, know that without any sort of proof to back it up, this feat falls flat.

My first solution to this problem was to provide two PDF files, as part of my Train Your Brain and Entertain CD-ROM, that constitute an 8400-year perpetual calendar. From the comments I've received, many suggest that this calendar is great in any place you might have other books, such as home or school. However, it's not handy to carry when you're just out and about.

That's why I developed a far more portable version! The new version is a Perpetual Calendar for your iPod, iPhone, PDA or cell-phone!

The calendar comes as a series of 176 .JPG images, with a resolution of 360 by 270. For your iPod or iPhone, you load them in as you would any other photos, via iTunes. If you have another cell phone or PDA in which you can display .JPG images, you can load these images as per your particular unit's instructions.

Once you have them loaded in, and accessible in numerical order, the perpetual calendar itself is easy to use. The first 8 pages are index pages, each of which list 50 years and a letter. Using our earlier September 6th, 2008 example, you would scroll to the 2000 - 2049 index to find the letter corresponding to 2008 (images below are at full size):

The next 168 images are images of individual months, each with a letter next to it. Since 2008 corresponds to J, and we're looking for September, we scroll through the images to find the one labeled September J:


This way, you can show that September 6, 2008, really does fall on a Saturday!

I have two important tips for using these images effectively. First, load the images in the numerical order in which they're named. Properly ordered, you should see the 8 index pages first, running in order from 1800 - 1849 to 2050 - 2099, followed by the calendar pages running from January A, then February A and so on up through December N. This way, you can find the page you need quickly and effectively.

Second, let the person who gave you the date see the entire process, so that they know that the calendar is accurate. If they want to see another date, such as today, for which they do know the day of the week, you can show them that date, as well.