18 (number)

← 17 18 19 →
← 10 11 12 13 14 15 16 17 18 19 → List of numbers — Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	eighteen
Ordinal	18th (eighteenth)
Factorization	2 × 32
Greek numeral	ΙΗ´
Roman numeral	XVIII
Binary	100102
Ternary	2003
Quaternary	1024
Quinary	335
Senary	306
Octal	228
Duodecimal	1612
Hexadecimal	1216
Vigesimal	I20
Base 36	I36

This article is about the number eighteen. For the year, see 18.

Eighteen is a number. It comes between seventeen and nineteen, and is an even number. It is divisible by 1, 2, 3, 6, 9 and 18. In most countries it is the age of majority, age of consent, and voting age.

In Roman numerals, 18 is written as XVIII.

The number 18 has many multiples such as: 36, 54, 72, 90, 108, and so on. The prime factorization of 18 is 3x3x2 in expanded form, and 2x3² in factored form.