75 (number)

In mathematics

• the fourth ordered Bell number, and counts the number of weak orderings on a set of four items.
• the sum of the first five pentagonal numbers, and therefore a pentagonal pyramidal number.
• an nonagonal number.
• a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 7, 5, 12, 17, 29, 46, 75...
• a self number because there is no integer that added up to its own digits adds up to 75.

In other fields

• The atomic number of rhenium
• The age limit for Canadian senators
• 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