Dozenal Society of America

Beginner to Dozenal?

Are you interested in using different number bases, or you’re studying number bases in school? This is a great place to start! Particularly if you're interested in dozenal (also called duodecimal, or base twelve), you've come to the right place!

Don’t even know what we mean by dozenal? Check out Eggsactly a Dozen.
Got an idea about dozenal, but not very much? Try A Brief Introduction to Dozenal Counting.
For an impressive demonstration of the beauty of dozenal multiplication tables, take a look at Multiplication in Base Twelve.
To see how much easier dozenal makes divisibility, check out dozenal divisibility tests.
After a while, you might want to practice your dozenal arithmetic.
Learn how to convert decimals to dozenals and back again by visiting Decimal-Dozenal Conversion Rules.

Not to mention our huge selection of articles and books. Soon, you'll be using twelve as a number base, multiplying and dividing, adding and subtracting, just as well (better!) than you ever did in decimal.

THIS SITE WAS SUBSTANTIALLY REORGANIZED IN JANUARY 120A_z (2026_d).

Content on this site has been moved to new locations, but old links will still be honored and redirected.

For an explanation of the notational changes on this site, see the new, expanded footer below; as well as this editorial, and this article, both from 11BB_z (2015_d). The DSA continues to endeavor to use the Pitman ten and eleven digits in The Duodecimal Bulletin and other publications, where we can take advantage of advanced typesetting software. Unfortunately, in HTML web pages, font support for the Pitman digits has yet to penetrate to all browser platforms, particularly mobile phones. To ensure readability for all visitors here, this site must resort to using the “Computerese” digits A and B.

The so-called “Computerese” digit set includes the entire Latin-1 alphabet A through Z on top of the Hindu-Arabic digits 0 through 9. This allows it to natively represent bases up to three-dozen. This is supported by computing technology such as the BASE function in Microsoft Excel or Google Sheets. In the interest of promoting an equitable and comprehensive approach to numeric bases, with “least-change” in the meanings of digits across all bases, we have discontinued use of the letters X (or T) and E for dozenal digits ten and eleven. We assert that dozenal’s combination of superior divisibility and human-manageable size make it the most practical base for human use. These advantages of dozenal are not dependent on superficial cosmetics of notation.