20 (number): Map

Map showing all locations mentioned on Wikipedia article:

"Twenty" redirects here. For the village in England, see Twenty, Lincolnshire.
20 (twenty) is the natural number following 19 and preceding 21. A group of twenty units may also be referred to as a score.

In mathematics

• An icosahedron has 20 faces. A dodecahedron has 20 vertices.
• 20 can be written as the sum of three Fibonacci Numbers uniquely, i.e. 20 = 13 + 5 + 2.
• The product of the number of divisors and the number of proper divisors of 20 is exactly 20.

In science

Biology

• The number of proteinogenic amino acids that are encoded by the standard genetic code.
• In some countries, the number 20 is used as an index in measuring visual acuity. 20/20 indicates normal vision at 20 feet, although it is commonly used to mean "perfect vision" (Note that this applies only to countries using the Imperial system. The metric equivalent is 6/6). When someone is able to see only after an event how things turned out, that person is often said to have had "20/20 hindsight".
• There are 20 baby teeth in the deciduous dentition.

Age 20

• Twenty is the age of majority in Japanese tradition. Someone who is exactly twenty years old is described as hatachi
• The age to be a adult in some cultures.

20 is:

Historical years

20 A.D., 20 B.C., 1920, 2020, etc.

References

 Embed code: