Number 7

A page of the Numeropedia - the Special Encyclopedia of Numbers

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Number 7 in Flags   Number 7 in Geology  Number 7 in History  Number 7 in Math.     

Number 7 in Sports   Number 7 in Science & Tech.    Number 7   (More Math. pages)


[Astronomy]  The number of stars in the Big Dipper (Ursa Major) and also of stars in the Little Dipper (Ursa Minor).


[Astronomy]  The number of Apollo Lunar Landing missions: Apollo 11 to 17, 6 successful missions and 1 failed: Apollo 13.


[Astronomy]  The number of planets known in antiquity: Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn. And the days of the week were named after them.


[Biology]  The number of neck bones (cervical vertebrae) of a human body.


[Biology]  The number of neck bones of a giraffe, even of its long neck.


[Calendar]  The number of days in a week.  1 week = 7 days = 168 hours = 10,080 minutes = 604,800 seconds.


[Calendar]  The number of 31-day months in a (solar) year: January, March, May, July, August, October and December.


[Calendar]  September was meant the 7th month in Latin.


[Calendar]  July’s birthstone is ruby or carnelian (for freedom). 

 July’s flower is larkspur or water lily.

July’s full moon is named “Buck Moon”.


[Chemistry]  The atomic number of Nitrogen (N).


[Chemistry]  The Ph (hydrogen potential) of a neutral solution (like pure water). The Ph between 7 and 14 indicates alkalinity (or base). The Ph between 0 and 7 indicates acidity. The Ph scale was invented in 1907 by the Danish chemist Søren Peter Lauritz Sørensen (1868-1939).


[EECS]  The digit represented by the violet color by either first 2 bands or the exponent of 10 represented by that color of the 3rd band (i.e. multiplier is 107) in the electronic resistor/capacitor color code.


[Game]  The number of special markings on each side of the “river” on a Xiangqi (Chinese chess) board, 5 for Soldiers (Pawns) and 2 for Cannons.


[Game]  The number of numbered letter tiles used in the game of Scrabble is 100 and only 7 letters on each player’s rack at a time. The board consists of 15×15 = 225 squares.


[Language]  Prefixes: Sept-, Hept-…


[Language]  The number of letters in the longest word in Vietnamese language: nghiêng, which means “inclined”.


[Language]  The number of consonants in the Hawaiian alphabet: H, K, L, M, N, P and W.


[Library]  ISBN-0-07 is the International Standard Book Number for books published by McGraw-Hill.


[Library]  ISBN-7 is the International Standard Book Number for books published in China.


[Measure]  Mohs hardness scale for estimating the hardness of minerals or solid substances: diamond 10, corundum 9, topaz 8, quartz 7, orthoclase 6, apatite 5, fluorite 4, calcite 3, gypsum 2 and talc 1.


[Measure]  The 7 o’clock direction is 60o off the left-hand side to the back.


[Movie]  TY-Y7, one of 6 basic ratings in the U.S. motion picture rating system in 1997: TV-Y, TV-G, TV-Y7, TV-PG, TV-14 and TV-M, appearing for 15 seconds in the upper left corner of the TV screen at the beginning of each show or program, except news and sports programs.


[Movie]  Names of TV shows/series or movies: “Se7en”, “Seven Year Itch”, “The Seven Samurai”, “Seven Days in May”, “Seven Brides for Seven Brothers”, “Seven Doors to Death”, “Seven Brothers Meet Dracula”, “Seven Years in Tibet”, “Seven (2006)”, “The Seventh Seal”, “The Seventh Sign”, “Six Days, Seven Nights” and “7:35 in the Morning”.


[Movie]  The number of dwarfs of Snow White: Bashful, Doc, Dopey, Grumpy, Happy, Sleepy and Sneezy in “Snow White and the Seven Dwarfs”.


[Music]  The number of basic musical notes of major scale: C, D, E, F, G, A and B (or Do, Re, Mi, Fa, Sol, La and Ti, respectively).


[Phone]  International telephone dialing code for Russia, Armenia, Georgia, Kazakhstan and Ukraine.


[Phone]  The digit that can be dialed mnemonically by either letter P, R or S (or maybe Q) on the telephone keypad.


[Phone]  The number to key in text messaging on telephone keypad for letter P.


[Theology]  The number of deadly sins: pride, wrath, envy, sloth, lust, gluttony and avarice.


[Theology]  The number of heavenly virtues: prudence, temperance, justice, fortitude (which are known as the Four Natural or Cardinal Virtures) and charity, hope and faith (which are known as Three Theological Virtures).


[Theology]  The number of days of God’s Creation, according to the Holy Bible, Genesis 2:1-4: creating the whole universe and the Earth in 6 days and the 7th day was for rest. 


[Theology]  The number of gods of light and also the number of gods of darkness in ancient Egypt


[Theology]  The Seventh-Day Adventists branch of Christianity.


[Trivia]  A lucky number, as popular belief.


[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]  The 7th wedding anniversary is traditionally named copper (or wool, brass) anniversary. Modernly, it may be replaced by desk sets (or onyx).


[Trivia]  After 6 failed attempts by Mr. C. L. Griggs (Missouri) of naming his newly invented soft drink in 1920s, originally called Bib-label Lithiate Lemon-Lime Soda, he came up with the name: 7-Up. (Other version: 7-ounce can).


[Trivia]  The popular 5” photo print is of the size 5”×7”.


[Trivia]  One of popular binders: 7-ring binder.


[Trivia]  The number of nails on a horseshoe.


[Trivia]  7/24 or 24/7: open 24 hours day, 7 days a week.


[Trivia]  Morse code for number 7 is 2 dashes and 3 dots [ _ _ . . . ]

Flag semaphore signal for number 7 is that of letter G.


[World]  The number of years for a term of a French president.


[Movie]  James Bond 007, British spy agent, a fictional movie character.



[Measure]  1 gill= 7.21875inch3.

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.



[Chemistry]  Acidosis is a physiological condition that occurs when the Ph (hydrogen potential) of the blood falls below 7.35.



[Chemistry]  Alkalosis is a physiological condition that occurs when the Ph (hydrogen potential) of the blood rises above 7.45.



[EECS]  7.5(W, KW or MW) is one of standard numerical values for resistors (of tolerance class 5%).


[Measure]  The length of a standard pencil, including the tip eraser is 7.5 inches.


[Trivia]  The shorter side (inches) of the U.S. standard paper size “Executive” (10 in×7.5 in, 254 mm×190 mm).


[Trivia]  Iowa is the only U.S. state name starting with 2 vowels: “I” and “O”. , but even more interesting, in a French map in 1763, it was spelled as: “Ouaouiatonon”, starting with 7 vowels.


[Science] Sterling silver is an alloy containing at least 92.5% silver (and at most 7.5% other metal, such as copper).



[Measure]  The number of inches in a link: 7.92.

1 mile = 8 furlongs = 80 chains = 5280 feet = 8000 links = 63,360 inches. Chain (or Gunter’s chain or surveyor’s chain) is a unit used in surveying.