A page of the Numeropedia - the Special Encyclopedia of Numbers
... In Arithmetic, 1+1 = 2, in Computer Science, 1+1 = 0, but in Love, 1+1 = 1!
[Chemistry] The pH (hydrogen potential) between 0 and 7 indicates acidity. The pH between 7 and 14 indicates alkalinity (or base). The pH = 7 is of a neutral solution (like pure water). The pH scale was invented in 1907 by the Danish chemist Søren Peter Lauritz Sørensen, (1868-1939).
[Education] The number of points to which a course’s grade F is transferred, when computing a student’s GPA (general point average) in the popular 4.0-scale GPA system of most schools.
[EECS] The digit represented by the black color by either first 2 bands or the exponent of 10 represented by that color of the 3rd band (i.e. multiplier is 1) in the electronic resistor/capacitor color code.
[EECS] Nonce is a value used only once within a specified context
[Geology] The 0o meridian (longitude line) goes through Greenwich Royal Astronomical Observatory, London, England, established in 1675 by King Charles II. The standard time of this meridian is Greenwich Mean Time (GMT), officially adopted on 1 November 1884 at the International Meridian Conference in Washington D.C. Technically, GMT no longer exists and now usually replaced/renamed by Universal Time (UT), which used officially by scientists at North and South Poles.
[Geology] The 0th parallel (0o latitude line), both North and South, is the Equator.
[Gov.] The period (years) of the U.S. Censuses; i.e., only in calendar years ending with digit 0 (required by the U.S. Constitution).
[Language] None, nil, null, empty, vacant, Æ, naught…
[Library] ISBN-0 and ISBN-1 are the International Standard Book Number codes for books published in English (U.S., United Kingdom, Australia, New Zealand, Canada, South Africa and Zimbabwe).
[Movie] Names of TV shows/series or movies: “Absolute Zero”, “ Suspect Zero”, “Day Zero”, “Less Than Zero”, “Zero Woman” and “Ground Zero”.
[Phone] The number dialed to call operator in the U.S. and Canada.
[Phone] The first digit of an NANPA/U.S. 3-digit area code cannot be 0 or 1. The smallest number assigned for an area code is, in fact, 201 for Jersey City and Hackensack, New Jersey. (NANPA: North American Numbering Plan Administration).
[Phone] A 7-digit number after an NANPA/U.S. 3-digit area code cannot start with 0nm, 1nm or 8 other 3-digit numbers: 211, 311, 411, 511, 611, 711, 811 and 911.
[Phone] Before 1995, the middle digit of an NANPA/U.S. 3-digit area code must be either 0 or 1. After this restriction was removed, the middle digit can be any digit from 0 to 8, cannot be 9, which are reserved for expansion codes in the future.
[Science] The original, balancing or starting point in place or time or the origin, practically or literally. Exception: no year 0, for conventional calendar, except for astronomy purposes.
[Science] The freezing point of water = 0 oC (Celsius or centigrade) = 32 oF (Fahrenheit) = 273.15 K (Kelvin).
[Science] The lowest temperature that the German scientist Gabriel Daniel Fahrenheit could obtain by mixing salt and ice: 0 oF = –17.78 oC.
[Sport] The starting score of a game of most sports.
[Sport] The ending time of a game at 0:00.
[Sport] In tennis, “love” means 0 or no score. It is from the French word, “l’oeuf”, for “egg”. One of systematically numerical scores in a [Game] of tennis: Love-15-30-40.
[Sport] The score of a par (or an even par) made for a hole in a game of golf.
[Tech.] The number to end a countdown.
[Tech.] The first (number system) digit in the 12-digit UPC Version A (Universal Product Code for North America) barcode is 0 or 7 for groceries, (followed by 5-digit manufacturing code, 5-digit product code and 1 check digit at the right end).
[Tech.] Credit cards and others identifying numbers, of any length a1…an–1, used the IBM check digit scheme of modulo 10. The scheme used the permutation p = (0)(1,2,4,8,7,5)(3,6)(9), so it can catch single digit errors and adjacent-digit tranposition errors, except that involve 0 and 9. The check digit an is added to the right end of the number, such that:
If n is even, p(a1)+a2+…+p(an–1)+an = 0 modulo 10,
If n is odd, a1+p(a2)+…+p(an–1)+an = 0 modulo 10.
[Trivia] The thumb and forefinger circle sign is used popularly in the Unites States as “OK”, but signifies “zero” in France and some other countries, “money” in Japan and a bad gesture in Latin American countries.
[Trivia] Morse code for number 2 is 5 dashes [ _ _ _ _ _ ].
Flag semaphore signal for number 0 is that for letter K.
[Zip] U.S. Postal Zip Code starting with digit 0: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island and Vermont. (Also: Puerto Rico, U.S. Virgin Islands and some APO/FPO).