180 (number)
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180 (one hundred eighty in American English, one hundred and eighty in British English) is the natural number following 179 and preceding 181.
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| Ordinal | One hundred [and] eighty |
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| Cardinal | 180th | ||
| Factorization |  |
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| Roman numeral | CLXXX | ||
| Binary | 10110100 | ||
| Duodecimal | 130 | ||
| Hexadecimal | B4 | ||
| Vigesimal | 90 | ||
[edit] In mathematics
One hundred [and] eighty is the sum of six consecutive primes (19 + 23 + 29 + 31 + 37 + 41), as well as the sum of eight consecutive primes (11 + 13 + 17 + 19 + 23 + 29 + 31 + 37).
The sum of Euler's totient function φ(x) over the first twenty-four integers is 180. Since 180 is divisible by the total number of its divisors, it is a refactorable number.
Using degrees (°) to measure angles, 180° is called straight angle, and makes a semicircle. 180° is equivalent to π rads. In normal space, the interior angles of a triangle add up to 180°.
180 is a Harshad number in base 10.
[edit] In other fields
- 180° also means antipode. For example, a "180-degree change" indicates a radical change.
- The maximum possible score in one turn at darts (three treble 20s).
- In astronomy, when two planets are 180 degrees apart, they are said to be in opposition. In astrology, this is an aspect that is considered to be negative in influence.
- The year AD 180 or 180 BC.
- A BMX trick where a rider rotates the bike and themselves through half a turn and lands, now rolling backwards.
