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Dozenal Society of America

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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.

Playfair on Dozenalism

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Title: Playfair on Dozenalism

Author: John Playfair

Year: 1067_z (1807_d)

Subject: An early English defense of the dozenal system.

John Playfair, in his comments on the French Revolution, notes that it found itself in the unique position of being able to cast off all the shackles of a past age, yet was still too timid to cast off the most obvious mathematical shackle of all: the decimal system. An early defense of dozenalism, conducted not long after the French Revolution as an aside in some comments on the definition of the meter.

This site and the documents on it are licensed under a Creative Commons Attribution 4.0 International License.

This site expresses numbers in alternative bases, particularly dozenal (also called duodecimal, or base twelve).
The DSA does not endorse any particular notation or pronunciation scheme for alternative bases.
However this site defaults to the following to ensure online readability across all platforms:
“Computerese” uppercase letters represent transdecimal digits: A = ten, B = eleven, C = twelve, etc.
Single-character subscripts annotate bases: d = decimal, z = dozenal, x = hexadecimal, etc., e.g., 2014_d = 11BA_z = 7DE_x.

(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 ...)_d
(0 1 2 3 4 5 6 7 8 9 A B 10 11 12 13 14 15 16 17 18 19 1A 1B 20 21 22 23 24 25 26 27 28 29 2A 2B 30 ...)_z
(0 1 2 3 4 5 6 7 8 9 A B C D E F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 23 24 ...)_x

PDF documents on this site reflect changing practices among dozenalists over the years:
Various symbols have been used to represent digits ten and eleven:
Dwiggins 𝒳 and Ɛ (often rendered X and E); Bell Telephone * and #; Pitman turned 2 and 3 (↊ and ↋); etc.
Italics were once used to distinguish dozenal numbers from decimal: e.g. 0.5 = 0.6.
Later, semicolon became a separate‑identity “dozenal point”, versus period as “decimal point”: e.g., 0.5 = 0;6.
However, subscript base annotations provide a more versatile solution that is least‑change: e.g., 0.5_d = 0.6_z = 0.8_x

Dozenal offers superior divisibility over decimal, which can make everyday arithmetic easier to learn:
⅙ = 0.2_z | ¼ = 0.3_z | ⅓ = 0.4_z | ½ = 0.6_z | ⅔ = 0.8_z | ¾ = 0.9_z | ⅚ = 0.A_z
⅙ = 0.1666…_d | ¼ = 0.25_d | ⅓ = 0.333…_d | ½ = 0.5_d | ⅔ = 0.666…_d | ¾ = 0.75_d | ⅚ = 0.8333…_d

EACH ONE, TEACH ONE.