Thirty

For the year A.D. 30, see 30.

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Thirty (30, XXX) is the natural number following twenty-nine and preceeding thirty-one. It is a primorial as well as the sum of the squares of the integers 1, 2, 3 and 4. It is a sphenic number. Its divisors are 1, 2, 3, 5, 6, 10, 15 and 30; its factorisation is

The Chinese word numeral for thirty is 三十; a polygon with thirty sides is called a tricegon. [1]

Thirty is also:

• The atomic number of zinc.
• The number of edges on the regular icosahedron and the regular dodecahedron.
• 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.

Thirty appears in the following names and titles:

• Thirty odd foot of grunts, the band fronted by actor Russell Crowe

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List of numbers

Twenty-eight - Twenty-nine - Thirty - Thirty-one - Thirty-two

Integer