189 (one hundred
ndeighty-nine) is the
natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''cardinal ...
following
188 and preceding
190
Year 190 ( CXC) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Aurelius and Sura (or, less frequently, year 943 ''Ab urbe condita'' ...
.
In mathematics
189 is a
centered cube number
A centered cube number is a centered figurate number that counts the number of points in a three-dimensional pattern formed by a point surrounded by concentric cubical layers of points, with points on the square faces of the th layer. Equival ...
and a
heptagonal number A heptagonal number is a figurate number that is constructed by combining heptagons with ascending size. The ''n''-th heptagonal number is given by the formula
:H_n=\frac.
The first few heptagonal numbers are:
: 0, 1, 7, 18, 34, 55, 81, 112 ...
.
The centered cube numbers are the sums of two consecutive
cubes
In geometry, a cube is a three-dimensional space, three-dimensional solid object bounded by six square (geometry), square faces, Facet (geometry), facets or sides, with three meeting at each vertex (geometry), vertex. Viewed from a corner it i ...
, and 189 can be written as sum of two cubes in two ways: and The smallest number that can be written as the sum of two positive cubes in two ways is
1729
Events
January–March
* January 8 – Frederick, the eldest son of King George II of Great Britain is made Prince of Wales at the age of 21, a few months after he comes to Britain for the first time after growing up in Hano ...
.
There are 189 zeros among the decimal digits of the positive integers with at most three digits.
The largest
prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways ...
that can be represented in 256-bit arithmetic is the "ultra-useful prime" used in
quasi-Monte Carlo method
In numerical analysis, the quasi-Monte Carlo method is a method for numerical integration and solving some other problems using low-discrepancy sequences (also called quasi-random sequences or sub-random sequences). This is in contrast to the regu ...
s and in some
cryptographic systems.
[ See Appendix B.]
See also
* The year
AD 189 or
189 BC
__NOTOC__
Year 189 BC was a year of the Roman calendar, pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Nobilior and Vulso (or, less frequently, year 565 ''Ab urbe condita''). The denomination 189 BC for this ...
*
List of highways numbered 189
*
References
{{DEFAULTSORT:189 (Number)
Integers