To help celebrate today's release of Train Your Brain and Entertain (TYBE), I'm introducing what I like to call the 400-Digit Pi Challenge!

In the TYBE software, one of the things you learn is how to memorize 400 digits of Pi, and it is taught so thoroughly, you can identify where each of those individual digits are located.

Now, what fun is learning this if you can't share and show this knowledge?

With this in mind, I've created a line of 400-Digit Pi Challenge shirts.

The front simply features the words "400-Digit Pi Challenge", with the sentence, "(I promise I won't peek.)" beneath it. The idea here, of course, it to get people to ask you about the nature of the challenge. What happens once they do? This is where the fun begins.

On the back of the shirts, there is a chart divided up in rows (A-J) and columns (1-10), exactly like the "Pi Chart" that comes with TYBE. You have someone look at the back and quiz you on the digits of Pi. They can do this in many ways:

* They give you a set of coordinates, such as A1 or B2, and you name the 4 digits at that point.

* They give a set of 4 digits, and you can tell them at which coordinates those digits are located.

* They can ask for a single digit located any number of digits (up to 400, of course) after the decimal point, and you can correctly state it.

* They can name just a row (A-J) or a column (1-10), and you can give the 40 decimals in that row/column!

This is not a trick that makes it seem like you've remembered 400 digits of Pi, but rather you are using the real digits of Pi, which can be verified by the nearest math geek, and you really are able to do it from memory!

If you master the 400-Digit Pi Challenge, leave a note and let me know of any good stories that come from demonstrating this feat!