| ||||
|---|---|---|---|---|
| Cardinal | eighteen | |||
| Ordinal | 18th (eighteenth) | |||
| Numeral system | octodecimal | |||
| Factorization | 2 × 32 | |||
| Divisors | 1, 2, 3, 6, 9, 18 | |||
| Greek numeral | ΙΗ´ | |||
| Roman numeral | XVIII, xviii | |||
| Binary | 100102 | |||
| Ternary | 2003 | |||
| Senary | 306 | |||
| Octal | 228 | |||
| Duodecimal | 1612 | |||
| Hexadecimal | 1216 | |||
| Hebrew numeral | י"ח | |||
| Babylonian numeral | 𒌋𒐜 | |||
18 (eighteen) is the natural number following 17 and preceding 19. It is an even composite number.
18 is a semiperfect number [1] and an abundant number. It is a largely composite number, [2] as it has 6 divisors and no smaller number has more than 6 divisors. There are 18 one-sided pentominoes. In the classification of finite simple groups, there are 18 infinite families of groups. [3]
In most countries, 18 is the age of majority, in which a minor becomes a legal adult. It is also the voting age, marriageable age, drinking age and smoking age in most countries, though sometimes these ages are different than the age of majority. Many websites restrict adult content to visitors who claim to be at least 18 years old.
21 (twenty-one) is the natural number following 20 and preceding 22.
30 (thirty) is the natural number following 29 and preceding 31.
70 (seventy) is the natural number following 69 and preceding 71.
90 (ninety) is the natural number following 89 and preceding 91.
26 (twenty-six) is the natural number following 25 and preceding 27.
72 (seventy-two) is the natural number following 71 and preceding 73. It is half a gross or six dozen.
84 (eighty-four) is the natural number following 83 and preceding 85. It is seven dozens.
34 (thirty-four) is the natural number following 33 and preceding 35.
36 (thirty-six) is the natural number following 35 and preceding 37.
54 (fifty-four) is the natural number and positive integer following 53 and preceding 55. As a multiple of 2 but not of 4, 54 is an oddly even number and a composite number.
92 (ninety-two) is the natural number following 91 and preceding 93
96 (ninety-six) is the natural number following 95 and preceding 97. It is a number that appears the same when turned upside down.
100 or one hundred is the natural number following 99 and preceding 101.
220 is the natural number following 219 and preceding 221.
100,000 (one hundred thousand) is the natural number following 99,999 and preceding 100,001. In scientific notation, it is written as 105.
225 is the natural number following 224 and preceding 226.
168 is the natural number following 167 and preceding 169.
1728 is the natural number following 1727 and preceding 1729. It is a dozen gross, or one great gross. It is also the number of cubic inches in a cubic foot.
240 is the natural number following 239 and preceding 241.
304 is the natural number following 303 and preceding 305.