A page of the Numeropedia - the Special Encyclopedia of Numbers

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All Numbers  &  [0-9]  & 10-19  20-29  30-39  40-49  50-59  60-69  70-79  80-89  90-99  100

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[Astronomy]  Mercury is the planet closest to the Sun and its angular separation from the Sun is always less than 28 degrees; Therefore, it is almost never out of the sun’s glare and off limits of observation even by the Hubble Telescope.

 

[Calendar]  The number of full days in February of a non-leap year.

 

[Calendar]  Canada’s National Day of Mourning is on 28 April.

 

[Chemistry]  The atomic number of Nickel (Ni).

 

[History]  The number of years the Berlin Wall lasted, since it was built in 1961 until the travel restrictions were lifted suddenly on 9 November 1989.

 

[History]  Texas became the 28th state of the U.S. on 29 December 1845.

 

[History]  The 28th U.S. President: Woodrow Wilson (Democrat, Virginia, 1913-1921).

His Vice President, Thomas Riley Marshall (Indiana), was the 28th U.S. Vice President.

 

[Language]  The number of letters in the Esperanto alphabet: A, B, C, Ĉ, D, E, F, G, Ĝ, H, Ĥ, I, J, Ĵ, K, L, M, N, O, P, R, S, Ŝ, T, U, Ŭ, V and Z.

 

[Language]  The number of letters in the Welsh alphabet (spoken in Wales): A, B, C, Ch, D, Dd, E, F, Ff, G, Ng, H, I, L, Ll, M, N, O, P, Ph, R, Rh, S, T, Th, U, W and Y. (No letters: J, K, Q, V, X and Z).

 

[Math.]  A triangular number (sum of all integers from 1 to 7): 28 = 1+2+3+4+5+6+7.

 

[Math.]  The 2nd perfect number: 28 = 1+2+4+7+14; i.e., a number equal to the sum of all of its proper divisors, including 1 (or also called aliquot divisors).  The first perfect numbers are: 6, 28, 496, 8128, 212(213–1) = 33550336, 216(217–1) = 8,589,869,056 and 218(219–1) = 137,438,691,328…

 

[Math.]  284 = 614,656 = (6+1+4+6+5+6)4.

285 = 17,210,368 = (1+7+2+1+0+3+6+8)5.

 

[Math.]  4,396 = 28×157, using each of 9 digits 1-9 once.

 

[Math.]  14×82 = 1,148 = 41×28.

 

[Math.]  The 3rd Keith number: 2, 8, 10, 18, 28, 46…

 

[Math.]  28,005,264 = (28+005264)2 = 52922 and 989,444,005,

264 = (989444+005264)2 = 994,7082 and 5292+994708 = 1000000.

 

[Math.]  The fifth postulate of planar (Euclidean) geometry proposed by mathematician Euclid in his works Elements is also known as Playfair’s axiom and was not used to prove the first 28 propositions in his book.

 

[Measure]  Length of a person’s forearms, from the elbow to the middle finger tips, is cubit: 1 cubit = 6 palms = 24 digits = 18 inches = 457.2 mm.

Roman cubit: 17.5 inches = 444.5 mm. Egyptian cubit  = 20.63 inches = 524 mm = 27.5 digits or often 28 digits.

A digit is the width of one finger, ¾ of an inch, 19.05 mm.

 

[Movie]  Names of TV shows/series or movies: “28 Days”, “28 Days Later” and “28 Weeks Later”.

 

[Science]  One of seven magic numbers in nuclear physics: 2, 8, 20, 28, 50, 82 and 126. They are the numbers of nucleons such that they are arranged into complete shells within the atomic nucleus.

 

[Trivia]  Ancient Chinese astrologers divided the night sky into 31 regions, namely “Three Enclosures” (Tam Viên) and “Twenty-Eight Mansions” (Nhị Thập Bát Tú). These mansions are grouped by four 7-mansion symbols for four directions: Azure Dragon of the East, Black Tortoise of the North, White Tiger of the West and Vermillion Bird of the South.

 

[Trivia]  Imaginary rhythms have 23-day “physical” cycles, 28-day “emotional” cycles and 33-day “intellectual” cycles. The complete rhythm cycle is 21,252 days (over 58 years).

 

[Trivia]  The U.S. President's White House has 132 rooms, 35 bathrooms, 28 fireplaces, 8 staircases and 3 elevators.

 

[World]  The ISO country code for Antigua and Barbuda is 028. (ISO-3166)

 

28.349

[Measure]  28.3495231 g (grams) = 1 oz (ounce).

U.S. customary units for weight measures: 35.274 oz (ounces) = 2.20462 lb (pounds) = 1 kg (kilogram & 16 ounces = 1 lb (pound).

 

28.41

[Measure]  1 fluidounce = 28.413075 ml (milliliters). British imperial units for dry and liquid measures: 1 bushel = 4 pecks = 8 gallons = 32 quarts = 64 pints = 256 gills = 1280 fluidounces = 36.368736 liters.

 

28.651

[Sport]  The optimum length (28.6512 meters = 94 feet) of a basketball court. The international court is 2 feet 2 inches shorter than the NBA court.

 

28.875

[Measure]  1 pint = 28.875 inch3.

U.S. customary units for liquid measures: 1 gallon = 4 quarts = 8 pints = 32 gills = 128 fluid ounces = 1024 fluid drams = 61440 minims = 3.785411784 liters = 231 inch3.