Deca (International spelling as used by the International Bureau of Weights and Measures; symbol: da) or deka (American spelling) is a decimal unit prefix in the metric system denoting a factor of ten. The term is derived from the Greek déka (δέκα) meaning ten.
The prefix was a part of the original metric system in 1795. It is not in very common usage, although the decapascal is occasionally used by audiologists. The decanewton is also encountered occasionally, probably because it is an SI approximation of the kilogram-force. Its use is more common in Central Europe. In German, Polish, Czech, Slovak, and Hungarian, deka (or deko) is common, and used in self-standing form, always meaning decagram. A runway number typically indicates its magnetic azimuth in decadegrees.
Before the symbol as an SI prefix was standardized as da with the introduction of the International System of Units in 1960, various other symbols were more common, such as dk (e.g., UK and Austria), D (e.g., Germany, Eastern Europe), and Da. For syntactical reasons, the HP 48, 49, 50 series, as well as the HP 39gII and Prime calculators use the unit prefix D.
See also Edit
- Decimal multiples and submultiples of SI units Archived 2019-03-30 at the Wayback Machine, 2006, SI Brochure: The International System of Units (SI), 8th edition
- Guide for the Use of the International System of Units (SI), 1995, NIST Special Publication 811
- HP 48G Series – User's Guide (UG) (8 ed.). Hewlett-Packard. December 1994 . HP 00048-90126, (00048-90104). Retrieved 2015-09-06.
- HP 50g graphing calculator user's guide (UG) (1 ed.). Hewlett-Packard. 2006-04-01. HP F2229AA-90006. Retrieved 2015-10-10.
- HP Prime Graphing Calculator User Guide (UG) (PDF) (1 ed.). Hewlett-Packard Development Company, L.P. October 2014. HP 788996-001. Archived from the original (PDF) on 2014-09-03. Retrieved 2015-10-13.
- "National Geographic TV Shows, Specials & Documentaries".
- "On the extension of the range of SI prefixes". 18 November 2022. Retrieved 5 February 2023.
- "Metric (SI) Prefixes". NIST.