90 (number)

90 ( ninety or ninety ) is the Entier naturalness which follows 89 and which precedes 91.

In mathematics

90 is:

the nap of the squares of the integers from 2 to 6.
Since 90 is the sum of its unit dividers (by excluding itself), it is a unit Perfect number.
It is a oblong Nombre.
Since 90 is divisible by the sum of its figures in bases 10, it is a Nombre Harshad.
It is also a Anti-indicator.

In Euclidean space, the interior angles of a square measure 90 degrees each one. Also, in a right triangle, the angle opposed to the hypotenuse measures 90 degrees, the sum of the two other angles make a total of 90 for a total sum of 180 degrees.

In other fields

90 is also:

the Atomic number of the Thorium, a Actinide.
the number of the Interstate 90 , a highway which starts from Washington to reach the state of the Massachusetts.
the international telephone indicative to call the Turkey.
the number of the European highway E90 which starts from Lisbon to the Portugal to reach Habur close to the Iraq.
the identifier ISBN for the books published in Holland,
speed limit in France to which one must roll on the secondary axes (in km/h).
maximum speed except agglomeration in Belgium (in km/h).
the n° of the French Department of the Territory of Belfort.
historical Years: -90, 90 or 1990.

Linguistics

With the Middle Ages, there was habit in France to count of twenty into twenty. Also one found the forms came and say (30), two wines (40), three wines (60), four wines (80), etc Saint Louis founded, for example, the old people's home of Quinze-vingts (of the 300 blind men). This system, known as “vigesimal”, was used by the Celts, the Norman ones and to a lesser extent by the Danes), and it is possible that one or the other of these people introduced it as a Gaulle.

As of the end of the Middle Ages, the concurrent forms thirty, forty, fifty, sixty are spread victoriously. Why the use stop does in if good way? No explanation is really convincing . Perhaps one tested the need to preserve the mark of a “mental calculation” adapted better to the great numbers (70=60+10, 80=4×20, 90=80+10). Remain the share of the chance and the arbitrary one, with which any historian of the language knows well that it is necessary for him to compose…

It is at the 17th century , under the influence of Vaugelas and Household, that the Academy and the other authors of dictionaries adopted the forms seventy definitively, eighty, ninety instead of seventy, octante, ninety. It should be noted however that the words seventy, octante, ninety appear in all the editions of the Dictionary of the French Academy. Still advised by the official Instructions of 1945 to facilitate the training of calculation, they remain known in the use spoken about many areas of the East and the South of France, like in Acadie. They are official in Belgium and Switzerland (except, however, octante, which was supplanted by eighty - in Belgium and Switzerland - and huitante - in Switzerland - so much in the everyday usage than in the administrative teaching or texts). Nothing prohibits to employ them, but compared to the everyday usage in France, they are perceived like regional or out-of-date.

Source: www.academie-francaise.fr

Ninety is used, amongst other things, in Suisse, Belgium and Savoy, even if it is not used any more usually in France.

The term comes from the Latin nonaginta which also gave Nonagénaire.

It takes again the logical construction of the Multiple S of ten regular (after about thirty): forty, fifty, sixty, seventy, Octante, ninety. Its incrementing is similar to that of these multiples: of “ninety and one” (91) with “nonante-neuf” (99).

Its use is " identique" with that of ninety: ninety and one, nonante-trois. Attention, however, not to say " nonante-treize".

See too

70 and 80

Zh-yue: 90

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