Number 89

A page of the Numeropedia - the Special Encyclopedia of Numbers

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[Biology]  Sunflower seed heads normally has 55 spirals going clockwise and 89 going counterclockwise.

 

[Chemistry]  The atomic number of Actinium (Ac). There are 15 elements in the Actinide series: Actinium (89) to Lawrencium (103).

 

[Gov.]  The U.S. President’s Air Force One is flown by the presidential aircrew, maintained by the Presidential Maintenance Branch and assigned to the U.S. Air Force–Air Mobility Command’s 89th Airlift Wing, Andrews Air Force Base, Maryland.

 

[Library]  ISBN-89 is the International Standard Book Number for books published in Korea.

 

[Math.]  89 = 81+92.

 

[Math.]  One of only four 2-digit prime numbers whose digits are consecutive: 23, 43, 67 and 89.

 

[Math.]  A prime number. A Mersenne exponent: 289–1 is the 10th Mersenne prime number.

 

[Math.]  40,578,660 = 2×2×3×3×5×17×89×149, where each digit 1-9 appears exactly twice.

 

[Math.]  The 11th Fibonacci number.

 

[Math.]  A prime number of consecutive digits: 23,456,789 and its “partitions” 23, 4567 and 89 are also all prime numbers.

 

[Math.]  893 = 704,969  = (7+04+9+69)3

894 = 62,742,241  = (6+2+74+2+2+4–1)4

895 = 5,584,059,449  = (5+5+8+4+0+5+9+4+49)5

897 = 44,231,334,895,529  = (4+4+2+3+1+33+4+8+9+5+5+2+9)7

 

[Math.]  The reciprocal 1/89 = Sn(Fn×10–(n+1)) = 0.011235955…, where Sn is the infinite sum which n runs over all positive integers and Fn is the nth Fibonacci number.

 

[Math.]  The reciprocal of numbers in the series 89, 9899, 998999… (i.e, of the form (102n–10n–1), for n>0) contains n rightmost digit of the first nth Fibonacci numbers up to the second biggest n-digit Fibonacci number:

1/89 = 0.011235955…

1/9899 = 0.000101020305081321345590…

 

[Math.]  The first Markov numbers are 1, 2, 5, 13, 29, 34, 89, 169, 194, 233…

 

[Tech.]  Octane (R+M)/2 antiknock index rating of unleaded gasoline for automobiles in the U.S.: 87, 88, 89, 90 and 91.