75 (number)
Appearance
75 (seventy-five) is the natural number following 74 and preceding 76.
| ||||
---|---|---|---|---|
Cardinal | seventy-five | |||
Ordinal | th | |||
Numeral system | 75 | |||
Factorization | ||||
Divisors | 1, 3, 5, 15, 25, 75 | |||
Greek numeral | ΟΕ´ | |||
Roman numeral | LXXV | |||
Binary | 10010112 | |||
Ternary | 22103 | |||
Senary | 2036 | |||
Octal | 1138 | |||
Duodecimal | 6312 | |||
Hexadecimal | 4B16 |
In mathematics
As the sum of the first five pentagonal numbers, 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).
In other fields
Seventy-five is also:
- Diamond anniversary[citation needed]
- The atomic number of rhenium
- The age limit for Canadian senators[citation needed]
- Municipal Okrug 75, a municipal okrug of Frunzensky District of Saint Petersburg, Russia
- A common name for the Canon de 75 modèle 1897, a French World War 1 gun
- The departement number of the city of Paris
- An online South African based photography website called 75