secret behind the number 13

Columbia Space Shuttle sent into space on 16-01-2003 (1+6+0+1+2+0+0+3 = 13) exploded during reentry and all crew members (including Kalpana Chawla of India) died. 


SADDAM HUSSEIN contain 13 letters (S,A,D,D,A,M,H,U,S,S,E,I,N) and was captured on 13 ^th December, 2003.  

There was an explosion of an oxygen tank of Apollo 13, which was on its way to moon. The explosion occurred on April 13, 1970.

Alexander wanted to be a God and accordingly made a 13^th statue on the place of his capital. He died and people considered that his will to be a 13^th God (12 gods, one for each month were known) was the reason of his death. After that this number was considered as unlucky.

In a British study published in the British Medical Journal in 1993, a comparison was made between the ratios of traffic volume to number of accidents on two different days i.e. Friday 6^th and Friday 13^th. It was concluded that though the traffic volume was less on Friday 13^th, the number of hospitalizations due to accidents were more. 

• Some people won't go to work on Friday the 13^th.
• Some people won't eat in restaurants on Friday the 13^th
• Some people may not like wedding on Friday the 13^th.
• Some people don't like to travel on Friday the 13^th.
• Many buildings don't have 13^th floor. Many hotels don't have a room with number 13^th. It is sometimes called as 12A.
• According to superstition, any one with 13 letters in their name is regarded to have Devil's luck.

BUT  SOMETHING INTERESTING BEHIND THE NUMBER 13   

• Reverse of the square of 13 is the same as the square of the reverse of 13 i.e. 13²= 169; on reversing 169, we get 961 which is the same as the square of reverse of 13 i.e. 31² = 961.
  
  13 x 13 = 169
  31 x 31 = 961
  
  
  
  Number 13 is the smallest prime number which can be expressed as the sum of the squares of two prime numbers i.e.
  
  13 = 2² + 3²
  
  
  
  From number 13 if we subtract the sum of its digits, we get a perfect square i.e.
  
  13 - (1 + 3) = 9 = 3²
  
  
  
  The number 169 which is perfect square can be expressed as sum of two square i.e.
  
  
  169 = 13² = 5² + 12²
  
  The number 169 can be expressed by number of its two block i.e. 16 and 9 which are perfect squares as follows:
  
  
  169 = (16 + 9) + (16 x 9)
  
  
  
  The reciprocal of number 13 gives
  
  
  

  1/13 = 0.076923076923076923...

  i.e. the number 076923 repeating indefinitely. This number 76923 is one of the most curious numbers in mathematics.On multiplying the number 76923 by successive multiples of 13, the following beautiful pattern is obtained.
  
  

  76923	x	13	=	0999999
  76923	x	26	=	1999998
  76923	x	39	=	2999997
  76923	x	52	=	3999996
  76923	x	65	=	4999995
  76923	x	78	=	5999994
  76923	x	91	=	6999993
  76923	x	104	=	7999992
  76923	x	117	=	8999991
  76923	x	130	=	9999990

  
  
   
  
  
  
  ^{SOME   OTHER INTERESTING} 
  
  
  
  
  
  • The premier of many countries is designated as PRIME MINISTER containing exactly 13 letters.
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  • Some other common designations containing 13 letters are CHIEF MINISTER, CHIEF ENGINEER, VICE PRINCIPAL etc.
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  • Some of the mathematical terms containing 13 letters are PERPENDICULAR, CIRCUMFERENCE, ANTILOGARITHM, APPROXIMATION, QUADRILATERAL and INDETERMINATE. 
  •  
  • The standard length of Broad Gauge Rail in India is 13 meters. 
  •  
  • Teen-hood starts from Thirteen. 
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  • 13 is also called a moon number because the moon moves approx. 13 degrees a day so there are 13 moon months in a year.
    
  • In Japan, the numbers 4 and 9 are considered unlucky, not because 13 can be represented as sum of these two perfect squares but because of their pronunciation. In Japanese, four is pronounced as shi which is the same pronunciation as death. Nine is pronounced ku which has the same pronunciation as torture.
  • There is always atleast one friday 13^th in each year. In some years, there are two and rarely three. Most recently in 1998 there were three friday 13^th. Next such year will be 2009.