Circa 300 BC, as part of theBrahmi numerals, various Indians wrote a digit 9 similar in shape to the modern closingquestion mark without the bottom dot. The Kshatrapa, Andhra and Gupta started curving the bottom vertical line coming up with a3-look-alike.[1] How the numbers got to their Gupta form is open to considerable debate. The Nagari continued the bottom stroke to make a circle and enclose the 3-look-alike, in much the same way that the sign @ encircles a lowercasea. As time went on, the enclosing circle became bigger and its line continued beyond the circle downwards, as the 3-look-alike became smaller. Soon, all that was left of the 3-look-alike was a squiggle. The Arabs simply connected that squiggle to the downward stroke at the middle and subsequent European change was purely cosmetic.
While the shape of the glyph for the digit 9 has anascender in most moderntypefaces, in typefaces withtext figures the character usually has adescender, as, for example, in.
The form of could possibly derive from the Arabic letterwaw, which in its isolated form (و) resembles the number 9.
The modern digit resembles an inverted6. To disambiguate the two on objects and labels that can be inverted, they are often underlined. It is sometimes handwritten with two strokes and a straight stem, resembling a raised lower-case letterq, which distinguishes it from the 6. Similarly, inseven-segment display, the number 9 can be constructed either with a hook at the end of its stem or without one. MostLCD calculators use the former, but someVFD models use the latter.
Casting out nines is a quick way of testing the calculations of sums, differences, products, andquotients ofintegers indecimal, a method known as long ago as the 12th century.[3]
9 is the only square number that is the sum of two consecutive, positive cubes:[4]
Non-intersectingchords between four points on a circle
9 is the sum of thecubes of the first two non-zero positive integers which makes it the first cube-sum number greater thanone.[6] A number that is 4 or 5modulo 9 cannot be represented as thesum of three cubes.[7]
9 is the largest single-digit number in thedecimal system.
The "nine dots" puzzle. The puzzle asks to link all nine dots using four straight lines or fewer, without lifting the pen.
Thenine dots puzzle is amathematical puzzle whose task is to connect nine squarely arranged points with a pen by four (or fewer) straight lines without lifting the pen or retracing any lines.
Nine is strongly associated with theChinese dragon, a symbol of magic and power. There are nine forms of the dragon, it is described in terms of nine attributes, and it has nine children. It has 117 scales – 81yang (masculine, heavenly) and 36yin (feminine, earthly). All three numbers are multiples of 9.[17]
To "go the whole nine yards" is to do something fully, despite any difficulty
To be "dressed to the nines" is to be as well dressed as possible
To be "on cloud nine" is to be in a state of complete bliss
Cats are said to have "nine lives", describing their ability to avoid or survive dangers
"A stitch in time saves nine", describing the greater ease of preparation and prevention as compared with repair or recovery
"K-9" is pronounced nearly identically tocanine and is used in many US police departments to denote thepolice dog unit. Despite the terms not beinghomophonous in other languages, many police and military units around the worldborrow the same designation from English.
The number 9 is revered in Hinduism and considered a complete, perfected and divine number because it represents the end of a cycle in thedecimal system, which originated from the Indian subcontinent as early as3000 BC.
Nine is the number associated with Satan inLaVeyan Satanism.Anton LaVey wrote in The Satanic Rituals that this is because nine is the number of theego since it "always returns to itself" even after being multiplied by any number.
Nines are a notation for expressing thepurity of a chemical.
Inchemical nomenclature, theprefix "non-" stands for the number nine, for example in molecular chains with nine atoms such as "nonane" for analkane with ninecarbon atoms. The prefixes play a role in the naming of molecules, especially inorganic chemistry to indicate the number of similar atoms or groups in the molecule (e.g. "nonan" for 9 carbon atoms, "nonavalent" for nine-valent.Nonapeptides are peptides that consist of nineamino acids.
