A page of the Numeropedia - the Special Encyclopedia of Numbers
[Biology] The number of noses of a slug.
[Biology] An animal/insect has an even number of legs: 2, 4, 6, 8, 10 or more. Animals/insects having 4 legs: dogs, cats, tigers…
[Biology] The number of taste zones in the human tongue: bitter (back), sour (back sides), salty (front sides) and sweet (front). Human tongue has about 10,000 taste buds.
[Biology] The number of chambers in a human heart: 2 atria (left and right) for collecting blood and 2 ventricles (left and right) for pumping it.
[Chemistry] The atomic number of Beryllium (Be).
[Game] The number of houses a player must buy on a property before he can buy hotel, in the board game “Monopoly”.
[Education] The number of points to which a course’s grade A is transferred, when computing a student’s GPA (general point average) in the popular 4.0-scale GPA system of most schools. A sign +/– may add/subtract 0.30 or 0.33 to the basic point, depending on schools.
[Education] The highest GPA in the 4.0-scale GPA system of most schools.
[Education] A 4th year college or high school student is a senior.
[Education] A 4-year college degree is typically a bachelor’s degree, either BA (Bachelor of Arts) or BS (Bachelor of Science).
[EECS] The digit represented by the yellow color by either first 2 bands or the exponent of 10 represented by that color of the 3rd band (i.e. multiplier is 104) in the electronic resistor/capacitor color code.
[EECS] The number of bits in a nibble. The number of nibbles in a word. The number of bytes in a doubleword. 1 doubleword = 2 words = 4 bytes = 8 nibbles = 32 bits.
[Game] The “15-puzzle” (Sam Loyd, 1878) is played on a 4´4 square board consisting of 15 square pieces, numbered 1-15 initially arranged in ascending order, with an empty square at the board’s bottom right corner.
[Language] Prefixes : Quadruple, Quad-, Quadri-, Tetra-, Tetro-, Quart-…
[Library] ISBN-4 is the International Standard Book Number for books published in Japan.
[Literature] The ancient Chinese Four Arts are: music, chess, poetry and painting.
[Medical] The number of groups of human blood: O, A, B and AB. Each blood group is also classified by its Rhesus factor (+) or (–) (also called Rh factor). Hence there are total 8 blood types: O+, O–, A+, A–, B+, B–, AB+ and AB–. Type O– is the universal donor. Type AB+ is universal recipient.
[Medical] In doctor’s
prescription, “bid “ means “twice a day”, “tid” means “three times a day” and
“qid”, “four times a day”, from Latin phrases “bis in die”, “ter in die” and
“quarter in die”, respectfully.
[Medical] The number of basic chemical units in the DNA (Deoxyribosenucleic Acid) structure: adenine (A), thymine (T), cytosine (C) and guanine (G). They form only 2 base pairs AT and CG.
[Military] A 4-star general is the highest-ranked general, currently in the U.S. military.
[Money] The number of quarters in one-dollar coin or bill. (U.S. currency).
[Money] 04:10 is the time that the 2 hands of the clock in the steeple of the Independent Hall, figured on the back of the U.S. $100 bill.
[Money] A Visa credit card number starts with digit 4.
[Movie] Names of TV shows/series or movies: “The Four Feather”, “Four Weddings and a Funeral”, “The Four Horsemen of the Apocalypse”, “Four Rooms”, "Four Brothers", “The Fourth Protocol”, “Fantastic Four” and “Four Christmases”.
[Music] The number of pairs of strings of a mandolin or bouzouki.
[Music] The number of strings of a violin/viola/cello.
[Music] Most popular banjos have 5 strings. Other models have 4 or 6 strings.
[Phone] The digit that can be dialed mnemonically by either letter G, H or I on the telephone keypad.
[Phone] The number to key in text messaging on telephone keypad for letter G.
[Theology] The Four Horsemen of the Apocalypse, mentioned in the Bible in chapter six of the Book of Revelation are traditionally named: Pestilence, War, Famine, and Death.
[Zip] U.S. Postal Service Zip+4 Code, (or 9-digit Zip+4 codes) instituted in 1983, is an expanded 5-digit Zip Code (instituted in 1963) plus a 4-digit add-on code to identify a geographic segment within the 5-digit delivery area for more efficient mail sorting and delivery.
[Library] First 3 digits (004, 005 and 006) in the Dewey Decimal Classification System call numbers for library books in Computer Science.
[World] The ISO country code for Afghanistan is 004. (ISO-3166)
4.3 and 4.7
[EECS] 4.3 and 4.7(W, KW or MW) are two of standard numerical values for resistors (of tolerance class 5%) between 4 and 5(W, KW or MW). 4.7mF (microfarads) is one of standard numerical values for capacitors.