duodecimal

 In 1944 the Duodecimal Society, advocating the use of the duodecimal for scientific purposes, was formed in New York. Although the society still exists, its name has changed to the Dozenal Society of America and the Dozenal Society of Great Britain. The word "dozenal" is used instead of "duodecimal" because the latter comes from Latin roots that express twelve in base-ten terminology.
A number system using the powers of 12, which are allotted place values as in the decimal system. The number written in decimals 4092 can be expressed as (2 × 123) + (4 × 122) + (5 × 121) + (0 × 120) or, in duodecimals, 2450. Fractions are expressed similarly. Two extra symbols are needed for this system to represent the numbers 10 and 11; these are generally accepted as X (dek) and Σ (el) respectively.

The advantage of this system can be realized by consideration of the integral factors of 10 and 12: 10 has two (2, 5) while 12 has four (2, 3, 4, 6). The fractions one-third and two-thirds are 0.4 and 0.8, respectively, in duodecimal – much simpler than the recurring expressions 0.3333... and 0.6666... in the decimal system.

The most common examples of everyday use of this system are the setting of 12 inches to the foot and 12 months to the year.

Related category

• TYPES OF NUMBER