| ||||
---|---|---|---|---|

Cardinal | seventy-five | |||

Ordinal | 75th (seventy-fifth) | |||

Factorization | 3 × 5^{2} | |||

Divisors | 1, 3, 5, 15, 25, 75 | |||

Greek numeral | ΟΕ´ | |||

Roman numeral | LXXV | |||

Binary | 1001011_{2} | |||

Ternary | 2210_{3} | |||

Quaternary | 1023_{4} | |||

Quinary | 300_{5} | |||

Senary | 203_{6} | |||

Octal | 113_{8} | |||

Duodecimal | 63_{12} | |||

Hexadecimal | 4B_{16} | |||

Vigesimal | 3F_{20} | |||

Base 36 | 23_{36} |

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

## In mathematics

**75** is:

- the fourth ordered Bell number, and counts the number of weak orderings on a set of four items.
^{[1]} - the sum of the first five pentagonal numbers, and therefore a pentagonal pyramidal number.
^{[2]} - an enneagonal number.
^{[3]} - 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]} - a self number because there is no integer that added up to its own digits adds up to 75.
^{[5]}

Excluding the infinite sets, there are 75 uniform polyhedra (or 76 if edges are allowed to coincide).

## In other fields

**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 1 gun
- The departement number of the city of Paris
- The number of balls in a standard game of Bingo in the United States

## References

**^**Sloane, N. J. A. (ed.). "Sequence A000670".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation.**^**Sloane, N. J. A. (ed.). "Sequence A002411".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation.**^**Sloane, N. J. A. (ed.). "Sequence A001106".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation.**^**Sloane, N. J. A. (ed.). "Sequence A007629".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation.**^**Sloane, N. J. A. (ed.). "Sequence A003052".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation.**^**“Who are our senators and what do they do?”, Parliament of Canada, retrieved 2014-02-02.