75 (number)

From HandWiki
Short description: Natural number
← 74 75 76 →
Cardinalseventy-five
Ordinal75th
(seventy-fifth)
Factorization3 × 52
Divisors1, 3, 5, 15, 25, 75
Greek numeralΟΕ´
Roman numeralLXXV
Binary10010112
Ternary22103
Quaternary10234
Quinary3005
Senary2036
Octal1138
Duodecimal6312
Hexadecimal4B16
Vigesimal3F20
Base 362336

75 (seventy-five) is the natural number following 74 and preceding 76.

In mathematics

75 is a self number because there is no integer that added up to its own digits adds up to 75.[1] It is the sum of the first five pentagonal numbers, and therefore a pentagonal pyramidal number, as well as a nonagonal number.[2][3]

It is also the fourth ordered Bell number, and a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 7, 5, 12, 17, 29, 46, 75...[4]

75 is the count of the number of weak orderings on a set of four items.[5]

Excluding the infinite sets, there are 75 uniform polyhedra in the third dimension, which incorporate star polyhedra as well. Inclusive of 7 families of prisms and antiprisms, there are also 75 uniform compound polyhedra.

In other fields

See also: List of highways numbered 75

Seventy-five is:

  • The atomic number of rhenium
  • The age limit for Canadian senators[6]
  • A common name for the Canon de 75 modèle 1897, a French World War I gun
  • The department number of the city of Paris
  • The number of balls in a standard game of Bingo in the United States

References