Duodecimal

A duodecimal system, also known as base twelve or dozenal (from dozen), is a positional numeral system using twelve as its base. In duodecimal, the number twelve is denoted "10", meaning 1 twelve and 0 units; in the decimal system, this number is instead written as "12" meaning 1 ten and 2 units, and the string "10" means ten. In duodecimal, "100" means twelve squared (144), "1,000" means twelve cubed (1,728), and "0.1" means one twelfth (0.08333...). Various symbols have been used to stand for ten and eleven in duodecimal notation; this page uses A and B, as in hexadecimal, which make a duodecimal count from zero to twelve read: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, 10. The Dozenal Societies of America and Great Britain (organisations promoting the use of duodecimal) use turned digits in their published material: 2 or ↊ (a turned 2) for ten (dek, pronounced /dɛk/) and 3 or ↋ (a turned 3) for eleven (el, pronounced /ɛl/). Following those numbers is twelve (do, pronounced /doʊ/). The number twelve, a superior highly composite number, is the smallest number with four non-trivial factors (2, 3, 4, 6), and the smallest to include as factors all four numbers (1 to 4) within the subitizing range, and the smallest abundant number. All multiples of reciprocals of 3-smooth numbers (⁠a/2b·3c⁠ where a,b,c are integers) have a terminating representation in duodecimal. In particular, ⁠+1/4⁠ (0.3), ⁠+1/3⁠ (0.4), ⁠+1/2⁠ (0.6), ⁠+2/3⁠ (0.8), and ⁠+3/4⁠ (0.9) all have a short terminating representation in duodecimal. There is also higher regularity observable in the duodecimal multiplication table. As a result, duodecimal has been described as the optimal number system. In these respects, duodecimal is considered superior to decimal, which has only 2 and 5 as factors, and other proposed bases...