Admittedly, learning the Day of the Week For Any Date feat in the classical way can be quite challenging.

Not long ago, I designed the 2011 Dice Calendar iPad Cases, iPhone Cases, and iPod Touch Cases in order to simplify the feat with a hidden cheat sheet.

Now, I've gone a step farther, and I'm releasing free backgrounds with a similar design for most Android and iOS devices!

As with the cases, the basic idea of the backgrounds is to appear as a simple dice design, while secretly communicating the information you need to determine the day of the week for any date given.

You can download the .ZIP file directly from this link, and you can also download it any time by going to the Downloads page, and clicking on Dice Calendar Backgrounds.

When you unzip the file, you'll get a master directory called dice_calendar. This directory contains all the graphics for any given year. How is this possible? There are only 14 possible years, 7 leap years starting on any given day of the week, and 7 normal years starting on any given day of the week.

Let's say you want the graphic for the year 2011. You'd click on the Normal_Year_Starts folder (since 2011 isn't a leap year), and then on 6_Saturday, since 2011 starts on a Saturday.

By contrast, 2012 is a leap year that starts on a Sunday, so you'd click on the Leap_Year_Starts, and then click on 0_Sunday to find the correct graphics.

Inside that folder, you'll find 6 .PNG files, each for a different device. For Android devices, there are graphics available in HVGA resolution (320 by 480), WVGA800 (480 by 800), and WVGA854 (480 by 854) resolutions. For iOS devices, there are iPhone pictures (320 by 480), iPhone Retina Display pictures (640 by 960), and iPad pictures (1024 by 1024). Choose the appropriate picture for your device.

You'll need to consult the manuals for your device for information on how to install your chosen picture. Keep in mind that these are intended only as lock screens, as the dice will be obscured by pages with apps on them. In addition, the resolution of the Android images is insufficient for use on the home screens.

For 2011, the graphic would look similar to the following one (as seen on the iPad version):



How do you use it to determine the date? The presentation I suggest is first asking for a date in the current year, then talking about how you used to get out your mobile device, turning it on (which gives you a glimpse of the dice calendar background), and looking at your built in calendar (which you never actually do). Mention that you've done this so much, that you know this year's calendar by heart, and to prove it, you give the correct day of the week (which your audience members can verify)!

How exactly is the dice calendar used to determine this? Except for only minor changes in presentation, it's done the same way as with the cases:



Of course, the cases will only be altered as the year changes. With the free backgrounds, you're ready for any year that comes along! I hope you find this simplified version fun and useful.