A page of the Numeropedia - the Special Encyclopedia of Numbers
[Astronomy] The number of known natural satellites of the planet Saturn: 18 named moons and 12 recently-discovered not-yet named moons.
[Calendar] The number of full days in a month (April, June, September and November).
[Calendar] The number of full days (29 or 30) in a month in the Chinese lunar (or lunisolar) year.
[Chemistry] The atomic number of Zinc (Zn).
[EECS] 30(W, KW or MW) is one of standard numerical values for resistors (of tolerance class 5%). 30pF (picofarads) is one of standard numerical values for capacitors.
[Game] The total number of “answers”/questions in each of the first stages of the TV’s “Jeopardy!” game show.
[Gov.] A U.S. senator must be a U.S. citizen over 30 years old and residing in the U.S. over 9 years.
[History] Wisconsinbecame the 30th state of the U.S. on 29 May 1848.
[History] The 30th U.S. President: Calvin Coolidge (Republican, Vermont, 1923-1929).
His Vice President, Charles Gates Dawes (Illinois, 1925-1929), was the 30th U.S. Vice President. There was no Vice President in the period 1923-1925.
[History] The European Thirty Years’ War (1618-1648) involved most of western European countries and was fought mainly in Germany, considered as war between Protestants and Catholics.
[History] Mark Anthony and Egyptian Queen Cleopatra died in the year 30 B.C. (She was born in 68-69 B.C., died at the age of 39 as the last Egyptian Pharaoh.
[History] The number of upright stones of the Sarsen Circle (only 16 remain standing), about 18 feet (33 meters), the most remarkable feature of Stonehenge on the Salisbury Plain in Wiltshire, England.
[Language] Prefixes : Trice-, Trige-…
[Language] The number of letters in the Bulgarian alphabet: A, Б, В, Г, Д, Е, Ж, З, И, Й, К, Л, М, Н, О, П, Р, С, Т, У, Ф, Х, Ц, Ч, Ш, Щ, Ъ, Ы, Ь, Э, Ю and Я. (No letters: Ë, Ы and Э).
[Measure] The number of minutes in half an hour. The number of seconds in half a minute.
[Measure] The 1 o’clock direction is 30o to the right-hand side.
The 4 o’clock direction is 30o off the right-hand side to the back
The 8 o’clock direction is 30o off the left-hand side to the back.
The 11 o’clock direction is 30o to the left-hand side.
[Money] A Diners Club card number starts with either 2 digits 30, 36 or 38.
[Money] The 30 DOW stocks are consisted of 3M, Alcoa, Altria Group, American Express, American International Group, AT&T, Boeing, Caterpillar, Citigroup, Coca-Cola, E.I. DuPont de Nemours, Exxon Mobil, General Electric, General Motors, Hewlett-Packard, Home Depot, Honeywell International, Intel, International Business Machines, Johnson & Johnson, JP Morgan Chase, McDonald’s, Merck, Microsoft, Pfizer, Procter & Gamble, United Technologies, Verizon Communications, Wal-Mart Stores and Walt Disney.
[Movie] Names of TV shows/series or movies: “13 Going To 30”, “30 Rock” and “30 Days of Night”.
[Phone] International telephone dialing code for Greece.
[Sport] One of systematically numerical scores in a game of tennis: Love-15-30-40.
[Sport] The height of the goal posts is at least 30 feet.
[Sport] In NFL football game, the kick-off return is set at 30-yard line of the kicking side.
[Sport] The circumference of a professional basketball: 29.5 to 30 inches.
[Sport] The loft angle of iron golf clubs is increased by 4o from the vertical, from 2-iron to 9-iron; for pitching wedge is 52o and sand wedge 58o.
2-iron: 18o 3-iron: 22o 4-iron: 26o 5-iron: 30o
6-iron: 34o 7-iron: 38o 8-iron: 42o 9-iron: 46o.
[Tech.] The HD-DVD will have memory capacity of 15, 30 or 50 GB (gigabytes).
(Toshiba's HD-DVD discs have 30 GB. Sony's Blu-Ray DVD discs have 50 GB.)
[Tech.] The “number system” code of an EAN-13 barcode for France’s products: 30, 31, 32, 33, 34, 35, 36 and 37.
[Tech.] The powers of commercial incandescent light bulbs: 300W, 100W, 75W, 60W, 40W, 30W, 15W, 7.5W and 3W.
[Tech.] The numbers of automobile engine oil SAE viscosity: 20W-20 (-40, -50), 10W-30 (-40) and 5W-20 (-30).
[Tech.] The formula to change from 2-letter contry code, say XY, (Alpha-2 list in the ISO Standard 3166 Contry Codes) to numeric version is: 1070+30X+Y, where A=1, B=2,…, and Z = 26.
[Trivia] Popular U.S. city street speed limits: 15, 25, 30, 35, 40, 45 or 50 miles/hour.
[Trivia] The 30th wedding anniversary is traditionally named pearl anniversary. Modernly, it may be replaced by diamond (or pearl jubilee).
[Trivia] Pack of soft drink cans or bottles: 4, 6, 12, 18, 20, 24, 30 or 36.
[Measure] The number of square yards in a square rod is 30.25
U.S. customary units for area measures: 1 acre = 160 square rods = 4,840 square yards = 43,560 square feet = 6,272,640 square inches = 4046.8564224 m2 & 1 square mile (1 section) = 640 acres = 2,589,988.11 m2 = 2.59 km2 = 259 hectares & 1 hectare = 2.471 acres = 10,000 m2 & 1 township = 36 square miles.
[Measure] 30.48cm (centimeters) = 1 foot.
(U.S. customary and metric units for linear measures).