30 (number)

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

In mathematics

30 is a composite, a regular number, a pronic number, and a primorial.

The SI prefix for 10³⁰ is Quetta- (Q), and for 10⁻³⁰ (i.e., the reciprocal of 10³⁰) quecto (q). These numbers are the largest and smallest number to receive an SI prefix to date.

Look up thirty in Wiktionary, the free dictionary.

In other fields

Thirty is used (as –30–) to indicate the end of a newspaper (or broadcast) story, a copy editor's typographical notation.

There are 30 days in the months April, June, September and November (and in unusual circumstances February—see February 30). Although the number of days in a month vary, 30 is used to estimate months elapsing.

30 years of marriage is marked by the pearl wedding anniversary.

History and literature

• Age 30 is when Jewish priests traditionally start their service (according to Numbers 4:3).
• One of the rallying cries of the 1960s student/youth protest movement was the slogan, "Don't trust anyone over thirty".
• In The Myth of Sisyphus the French existentialist Albert Camus comments that the age of thirty is a crucial period in the life of a man, for at that age he gains a new awareness of the meaning of time.

References