75 (number) - Definition and Overview

75 is the natural number following 74 and preceding 76.

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.

There are 75 uniform polyhedra.

In science

• The atomic number of rhenium

In astronomy,

Messier object M75, a magnitude 9.5 globular cluster in the constellation Sagittarius

The New General Catalogue object (http://www.ngcic.org/) NGC 75, a spiral galaxy in the constellation Pisces

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on -604 July 7 and ended on 694 August 26. The duration of Saros series 75 was 1298.1 years, and it contained 73 solar eclipses.

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -266 May 8 and ended on 1014 June 15. The duration of Saros series 75 was 1280.1 years, and it contained 72 lunar eclipses.

In other fields

Seventy-five is also:

• The designation of Interstate 75, a freeway that runs from Florida to Michigan.
• The registry of the U.S. Navy's nuclear aircraft carrier USS Harry S. Truman (CVN-75), named after U.S. President Harry S. Truman.
• The record for most game show wins, held by Ian Lygo. Also, the record for most game show appearances, currently a tie between Lygo and Ken Jennings.
• The year AD 75, 75 BC, or 1975.