75 (number)
Encyclopedia
75 is the natural number
following 74
and preceding 76
.
s, seventy-five is a pentagonal pyramidal number
. It is also an enneagonal number.
It is also a Keith number, because it recurs in a Fibonacci
-like sequence started from its base 10 digits: 7, 5, 12
, 17
, 29
, 46
, 75... But there is no integer that added up to its own digits adds up to 75, hence 75 is a self number
.
Excluding the infinite sets, there are 75 uniform polyhedra (or 76 if edges are allowed to coincide).
Natural number
In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...
following 74
74 (number)
74 is the natural number following 73 and preceding 75.A seventy-four was a third-rate warship with 74 guns.-In mathematics:Seventy-four is the twenty-first distinct semiprime and the eleventh of the form 2×q...
and preceding 76
76 (number)
76 is the natural number following 75 and preceding 77.-In mathematics:Seventy-six is a Lucas number, an automorphic number, a nontotient, a 14-gonal number, and a centered pentagonal number....
.
In mathematics
As the sum of the first five pentagonal numberPentagonal number
A pentagonal number is a figurate number that extends the concept of triangular and square numbers to the pentagon, but, unlike the first two, the patterns involved in the construction of pentagonal numbers are not rotationally symmetrical...
s, seventy-five is a pentagonal pyramidal number
Pentagonal pyramidal number
A pentagonal pyramidal number is a figurate number that represents the number of objects in a pyramid with a pentagonal base. The nth pentagonal pyramidal number is equal to the sum of the first n pentagonal numbers....
. It is also an enneagonal number.
It is also a Keith number, because it recurs in a Fibonacci
Fibonacci
Leonardo Pisano Bigollo also known as Leonardo of Pisa, Leonardo Pisano, Leonardo Bonacci, Leonardo Fibonacci, or, most commonly, simply Fibonacci, was an Italian mathematician, considered by some "the most talented western mathematician of the Middle Ages."Fibonacci is best known to the modern...
-like sequence started from its base 10 digits: 7, 5, 12
12 (number)
12 is the natural number following 11 and preceding 13.The word "twelve" is the largest number with a single-morpheme name in English. Etymology suggests that "twelve" arises from the Germanic compound twalif "two-leftover", so a literal translation would yield "two remaining [after having ten...
, 17
17 (number)
17 is the natural number following 16 and preceding 18. It is prime.In spoken English, the numbers 17 and 70 are sometimes confused because they sound similar. When carefully enunciated, they differ in which syllable is stressed: 17 vs 70...
, 29
29 (number)
29 is the natural number following 28 and preceding 30.-In mathematics:It is the tenth prime number, and also the fourth primorial prime. It forms a twin prime pair with thirty-one, which is also a primorial prime. Twenty-nine is also the sixth Sophie Germain prime. It is also the sum of three...
, 46
46 (number)
46 is the natural number following 45 and preceding 47.- In mathematics :Forty-six is a Wedderburn-Etherington number, an enneagonal number and a centered triangular number. It is the sum of the totient function for the first twelve integers. 46 is the largest even integer that can't be expressed...
, 75... But there is no integer that added up to its own digits adds up to 75, hence 75 is a self number
Self number
A self number, Colombian number or Devlali number is an integer which, in a given base, cannot be generated by any other integer added to the sum of that other integer's digits. For example, 21 is not a self number, since it can be generated by the sum of 15 and the digits comprising 15, that is,...
.
Excluding the infinite sets, there are 75 uniform polyhedra (or 76 if edges are allowed to coincide).
In other fields
Seventy-five is also:- DiamondDiamondIn mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
anniversary - The atomic number of rheniumRheniumRhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an average concentration of 1 part per billion , rhenium is one of the rarest elements in the Earth's crust. The free element has...
- The age limit for Canadian senators
- Municipal Okrug 75, a municipal okrug of Frunzensky District of Saint PetersburgSaint PetersburgSaint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
, Russia - A common name for the Canon de 75 modèle 1897Canon de 75 modèle 1897The French 75mm field gun was a quick-firing field artillery piece adopted in March 1898. Its official French designation was: Matériel de 75mm Mle 1897. It was commonly known as the French 75, simply the 75 and Soixante-Quinze .The French 75 is widely regarded as the first modern artillery piece...
, a French World War 1 gun - The departement number of the city of ParisParisParis is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...