// Workers AI · dad joke modeWhy was 30 a great party guest? It was 30-tiful.

"Thirty" redirects here. For other uses, see 30.

← 29 30 31 →
← 30 31 32 33 34 35 36 37 38 39 → List of numbers Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	thirty
Ordinal	30th (thirtieth)
Factorization	2 × 3 × 5
Divisors	1, 2, 3, 5, 6, 10, 15, 30
Greek numeral	Λ´
Roman numeral	XXX, xxx
Binary	111102
Ternary	10103
Senary	506
Octal	368
Duodecimal	2612
Hexadecimal	1E16
Armenian	Լ
Hebrew	ל
Babylonian numeral	𒌍
Egyptian hieroglyph	𓎐

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

In mathematics

30 is a square pyramidal number.

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.

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.