Digit

Digit (pronounced dij-it)

(1) In anatomy and zoology, a jointed body part at the end of the limbs of many vertebrates. The limbs of primates end in five digits, while the limbs of horses end in a single digit that terminates in a hoof.  In humans, digit is an alternative name for a finger or toe; dactyl.

(2) In zoology, a similar or similar-looking structures in other animals.

(3) As a historical unit of lineal measure, a unit of length notionally based upon the width of an adult human finger, standardized differently in various places and times (and still used as a measure in certain alcoholic spirits and among those fitting bras who recommend the finger as the gauge of the space between skin & fabric).  The most frequently cited is the English digit of 1/16 of a foot (about 19mm).  Prior to standardization, digit was used as a synonym of inch (the synonyms including “finger”, “fingerbreadth” & “fingersbreadth”).

(4) In modern mathematics, the whole numbers from 0 (zero) to 9 and the Arabic numerals representing them, which are combined to represent base-ten numbers; a position in a sequence of numerals representing a place value in a positional number system (ie any of the symbols of other number systems).

(5) In astronomy, the twelfth part of the sun's or moon's diameter; used often to express the magnitude of an eclipse.

(6) In geometry, a synonym for degree (1/360 of a circle) (obsolete).

(7) An index (obsolete).(7) An index (obsolete).

1350–1400: From the Middle English digit, from the Latin digitus (a fingerbreadth; a number); doublet of digitus.  The Latin from the primitive Indo-European deyǵ- (to show, point out, pronounce solemnly), a variant of the root deyḱ- & deik (to show; pronounce solemnly) from which Latin also gained dīcō (I say, speak talk) & dicere (to say, speak) and English picked up toe.  Fingers were thus “pointers & indicators” and digit gained the meanings related to mathematics and numbers; fingers were used for counting up to ten (and, with recycling beyond).  The finger or toe sense in English is documented from the 1640s but the date of origin is speculative.  Indo-European cognates include the Sanskrit दिशति (diśáti) (to show, point out), the Ancient Greek δείκνυμι (deíknumi) (to show) & δίκη (díkē) (manner, custom), the Old English tǣċan (to show, point out (source of the English teach)) and tācen (the English token).  Digit is a noun & verb, digitize is a verb and digital & digitigrade are nouns & adjectives; the noun plural is digits.

Great moments in digits

The phalanx of the ten digits of two human hands are presumed to have been the integers of the hand-held calculator and in this use it would have predated formal structures of language, the concepts of “one” and “two” the origin of mathematics.  All humans naturally having ten digits, the decimal (Base-10) numeral system emerged (apparently independently) in many ancient cultures although there was some intellectual transfer, the Greeks gaining the system from Egypt although neither the Greeks or Romans exclusively used Base-10, some industry-specific methods of calculation based on the capacity of the containers in traditional use.  In China, there’s evidence of use from the first century BC.  The familiar numerals (0, 1, 2, 3, 4, 5, 6, 7, 8, 9 & 0) which underpin all mathematics were developed by Arabic and Indian scholars although the elusive “0” wasn’t in widespread use until the ninth century. 

Zero though had a long history and texts from circa 300 BC detailing Babylonian mathematics display a placeholder symbol for zero in their positional numeral system (without which the representation of big numbers would practically have been impossible) although there is no evidence of the concept of zero existing as a stand-alone number.  Around the fifth century AD, Indian mathematicians documented why zero was so essential although it was a big country and there was no standardization in the symbolic representation of the value; the math however remains recognizably identical as one would expect.  Whether through the exchange of texts or (as many suspect is more likely) through the trade routes, the zero travelled east to the Islamic world where both Persian and Arabic mathematician published works explaining the implications of the still novel digit.  In the Medieval West, translations of the texts appeared but zero’s path to acceptance in Europe was slow and resisted, both by merchants and the Church, institutions with their own system, mastery of which was in the hands of an educated few.  However, so compelling were the advantages offered by adoption that by the thirteenth century, it was clear zero was here to stay.

Ten digit human hands might have been (more or less) universal but historically, Base-10 was not.  The Maya civilization used a vigesimal system (Base-20) and vigesimal components were in the counting systems of the Aztecs and some African cultures, the latter presumably an independent development.  The assumption of anthropologists is the Base-20 is a “fingers & toes” system and it does seem to be something restricted to warm climates where the removal of footwear doesn’t risk frostbite.  Nor were the hands always dealt with in multiples of five, the Yuki language of what is modern California uses Octal (Base-8) which counted the spaces between the fingers rather than the digits.  The ancient Mesopotamians (most famously the Babylonians & Sumerians) had a Sexagesimal (Base-60) system and that endures to this day in the measurement of time (60 seconds in a minute, 60 minutes in an hour) although there was an attempt to change that during the French Revolution (1789), the new republic introducing decimal time in 1793, seen as an act of democratic modernization which would include a programme to decimalize all units of measurement; the day became 10 hours long, an hour was 100 minutes and a minute 100 seconds.  However, the experiment did not prove a success, the critical mass of the old ways too embedded in the culture and the idea was abandoned in 1795 although the metric system did debut in 1799 and thrived, eventually world-wide (except in the US and a couple of quixotic hold-outs).  The Duodecimal (Base-12) system was used by the Mayans and in ancient Egypt and it too persists in commerce in the measures like dozen (12) and gross (12 dozen (144).  Binary (Base-2) of course runs the modern world because that is how (non-quantum) computers work, “0” & “1” being “on” & “off” respectively, most of what a computer does able ultimately to be reduced to a rapid succession of on/off transactions.  Nerds like Hexadecimal (Base-16) which uses the digits 0-9 and the letters A-F, representing values from 0 to 15.  Not the most unambiguous system, developers use hexadecimal numbers because in certain circumstances they make available an easier way to represent binary-coded values.

During an Aegean cruise in October 2016, Lindsay Lohan suffered a finger injury.  In this dreadful nautical incident, the tip of one digit was severed by the boat's anchor chain but details of the circumstances are sketchy although there was speculation that upon hearing the captain give the command “weigh anchor”, she decided to help but, lacking any background in admiralty jargon, misunderstood the instruction.

Detached chunk of the ring-finger's distal digit was salvaged from the deck and expertly re-attached by a micro-surgeon ashore, digit and the rest of the patient said to have both made full recoveries.  Despite the injury to the ring-finger, Ms Lohan still managed to find a husband so all's well that ends well.