A page of the Numeropedia - the Special Encyclopedia of Numbers
[Astronomy] The number of eclipse years (approximately) in a Saros cycle (used to calculate the solar and lunar eclipses): 6585 days 7 hours 23 minutes, which is exactly 223 synodic months, approximately 19 eclipse years (6585.78 days = 6585 days 18 hours 43.2 minutes).
[Biology] Each human foot has 26 bones, 33 joints, 107 ligaments and 19 muscles and tendons.
[Calendar] On average, 19 solar years (228 solar months) is almost exactly 235 lunar months, approximately: 19´365.2422 = 6939.6018 and 235´29.53 = 6939.55, (but also was given 6939.6884). It is called Metonic cycle, when all the phases of waxing and waning moon fall on the same days of the weeks for the whole solar year.
[Chemistry] The atomic number of Potassium (K).
[Flag] The number of gold stars on the Indiana state flag, representing the 19th state of the Union: 13 stars forming a circle encircling the torch, representing the 13 original states of the Union, 5 stars inside the circle for the next states ahead of Indiana joining the Union and the largest 19th star above the torch for Indiana itself.
[Flag] The number of stars around the seal on the Minnesota state flag, (5 groups of 4 stars except one of 3 stars), representing the 19th state after the 13 original states of the Union, making it the 32nd state of the Union.
[Game] The number of vertical lines and of horizontal lines of a Go board (or goban). In fact, the board is always slightly longer than it is wide. The Go game has 19 ´ 19 = 361 pieces, 180 white and 181 black. Go is called Weichi in China and Baduk in Korea.
[History] Indiana became the 19th state of the U.S. on 11 December 1816.
[History] The 19th U.S. President: Rutherford Birchard Hayes (Republican, Ohio, 1877-1881).
His Vice President, William Almon Wheeler (New York), was the 19th U.S. Vice President.
[History] The 19-gun salute is for U.S. Vice President, Prime ministers, ambassadors and cabinet/department chiefs. Other odd-number gun salutes (17, 15, 13, 11, 7 and 5) are for lower-level chiefs.
The 21-gun salute is for U.S. Presidents, chiefs of government or States or reigning royal family.
[Language] Prefixes: Enneadeca-, Decennov-…
[Language] The number of consonants in the Hangeul (Korean alphabet).
[Library] ISBN-0-19 is the International Standard Book Number for books published by Oxford University Press.
[Math.] A prime number. All numbers 19, 109, 1009, 10009 are prime and the next is 1000000009.
[Math.] An alternating sum/subtraction of factorials: 19 = 4!–3!+2!–1!.
[Math.] A Mersenne exponent: 219–1 = 524,287 is the 7th Mersenne prime number.
[Math.] The only known 7 prime numbers consisting of the repeated digits 1 are the numbers of 2, 19, 23, 317, 1031, 49,081 and 86,453 digits 1.
[Math.] The 19th Fibonacci number, 4181, is the first Fibonacci number with prime subscript that is not a prime number itself.
[Math.] The sum s(n) = 2^(2n)+3^(2n)+5^(2n) is always divisible by 19 and the sum t(n) = 2^(4n)+3^(4n)+5^(4n) is always divisible by 192 for any integer n³ 1: s(1) = 22+32+52 = 38 and t(1) = 24+34+54 = 722.
[Math.] Every integer can be a sum of at most 19 fourth power numbers.
[Math.] The 2nd Keith number: 1, 9, 10, 19, 29…
[Math.] 912 = 8281 = (82+8+1)2 = (8+2+81)2 and 19 = 8+2+8+1.
[Math.] The product of the first 8 consecutive prime numbers, divided by 10: 2×3×5×7×11×13×17×19/10 = 969,969 is a palindromic number.
[Math.] A supersingular prime numbers factors of the order of the Monster group M: 246×320×59×76×112×133×17×19×23×29×31×41×47×59×71
[Math.] The imaginary quadratic fields Q((–19)1/2) is one of only 9 UFDs (unique factorization domains) of form Q((–d)1/2), d = 1, 2, 3, 7, 11, 19, 43, 67 and 163.
[Movie] Name of TV show/series or movie: “K-19: the Widowmaker”.
[Music] The number of strings of the Vietnamese 19-stringed zither. Also, 16-stringed zither.
[Phone] The emergency telephone numbers dialing within Morocco are 15 and 19.
[Sport] In golf, the clubhouse is nicknamed the 19th hole.
[Sport] The score (or points) to win a ping-pong (table tennis) game or a volleyball game is 21, while the opposite player wins only 19 or less points.
[Tech.] The number of rings on a paper-binding plastic comb for the 11-inch side of a sheet of paper (of the standard size 8½-inch×11-inch).
[Tech.] The length (cm, centimeters) of a standard pencil, including the tip eraser.
[Trivia] Modernly, the 19th wedding anniversary is named bronze (or aquamarine) anniversary.
[Trivia] The oldest age for being a teenager (13-19 years old).
[Measure] A digit is the width of one finger, ¾ of an inch, 19.05 mm.
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.