30 (number)

30 (thirty) is the natural number following 29 and preceding 31.

In mathematics

It is a primorial as well as the sum of the squares of the integers 1, 2, 3 and 4. It is the first sphenic number and the first Giuga number. It is the sum of the first four squares, which makes it a square pyramidal number.

30 is the largest number such that coprimes smaller than itself are also prime. It is a Harshad number.

The Chinese word numeral for thirty is 三十.

A polygon with thirty sides is called a tricegon. [1] Both an icosahedron and a dodecahedron have 30 edges.

In other fields

Thirty is:

• The atomic number of zinc.
• The house number of 30 St Mary Axe (The Gherkin)
• The number of days in the months April, June, September and November.
• The number of moons of the planet Saturn.
• In years of marriage, the pearl wedding anniversary.
• The code for international direct dial phone calls to Greece.
• The designation of Interstate 30, a freeway that runs from Texas to Arkansas.
• Used to indicate the end of a wire service story.
• Part of the name of:
  • Thirty odd foot of grunts, the band fronted by actor Russell Crowe
• In the title of the movie 13 Going on 30, starring Jennifer Garner.
• Historical years: 30 A.D., 30 B.C., or 1930