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Dozenal Society of America
Promoting base twelve and alternative base mathematics
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The Dozenal Society of America
The DSA is a voluntary, nonprofit education corporation, organized for the conduct of research and education of the public in the use of dozenal (also called duodecimal or base-twelve) in calculations, mathematics, weights and measures, and other branches of pure and applied science.

Practice Your Dozenal Arithmetic

Test your dozenal arithmetic skills! Use "X" for ten and "E" for eleven. Remember not to calculate in decimal and convert the answer; calculate in dozenal to help you memorize the dozenal arithmetic facts. They are much easier and more regular in dozenal, so this should be a help in doing so.

Addition | Subtraction | Multiplication | Division