Lucky and unlucky

Lucky and unlucky

Unlucky 13

The number 13 is considered to be an unlucky number in some countries. It even has a specifically recognized phobia, Triskaidekaphobia, a word which was coined in 1911. The superstitious sufferers of triskaidekaphobia try to avoid bad luck by keeping away from anything numbered or labelled thirteen. As a result, companies and manufacturers use another way of numbering or labelling to avoid the number, with hotels and tall buildings being conspicuous examples (Thirteenth floor). 5  It's also considered to be unlucky to have thirteen guests at a table. Friday the 13th has been considered the unluckiest day of the month.

There are a number of theories behind the cause of the association between thirteen and bad luck, but none of them have been accepted as likely.

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

The Last Supper

At Jesus Christ's last supper, there were thirteen people around the table, counting Christ and the twelve apostles.

Knights Templar

On Friday the 13th of October, 1307, King Philip IV of France ordered the arrest of the Knights Templar.

Full moons

A year which contained 13 full moons instead of 12 posed problems for the monks who were in charge of the calendars. "This was considered a very unfortunate circumstance, especially by the monks who had charge of the calendar of thirteen months for that year, and it upset the regular arrangement of church festivals. For this reason thirteen came to be considered an unlucky number."

However, in a typical century, there will be about 37 years which have 13 full moons compared with 63 years with 12 full moons, and typically every third or fourth year would have 13 full moons, making it a reasonably common occurrence, unlikely to tax monks any more than leap years.

A repressed lunar cult

In ancient cultures, the number 13 represented femininity, because it corresponded to the number of lunar (menstrual) cycles in a year (13 x 28 = 364 days). The theory is that, as the solar calendar triumphed over the lunar, the number thirteen became anathema.

Lucky 13

Several successful sports figures have worn the number 13. Ozzie Guillén, manager of the 2005 World Series Champion Chicago White Sox, has worn the number throughout hisbaseball career. Alex Rodriguez began wearing it upon joining the New York Yankees (three, the number he had previously worn, is retired by the Bronx Bombers to honor Babe Ruth).Dan Marino, an American football player known for passing the 2nd most yards in NFL history, wore the number 13. Basketball great Wilt Chamberlain wore the number 13 on his jersey throughout his NBA career. Also, FIBA rules require a player to wear the number in international competitions (only numbers from 4 to 15 could be worn, and as there are 12 players, one must wear 13); Chris Mullin, who wore No. 20 in college and No. 17 in the NBA, wore No. 13 for both (1984 and 1992) of his Olympic appearances. Shaquille O'Neal wore No. 13 in 1996;Tim Duncan wore No. 13 in 2004. Steve Nash is currently wearing it for the Phoenix Suns. Yao Ming wore it in the 2008 Olympics in Beijing. Mats Sundin, Pavel Datsyuk, Bill Guerin, and Michael Cammalleri wear 13 in the NHL. One of Iceland's all time best handball players, Sigurður Sveinsson, wore the number 13 when he played for the national team. In association football, both Gerd Müller and Michael Ballack have favoured the number 13, among others.

In Italy, 13 is also considered to be a lucky number, although in Campania the expression 'tredici' (meaning 13) is said when one considers their luck to have turned for the worse.

Some people even have 13 tattooed onto them to represent the lucky number.

What is so interesting about 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

Where 2, 3, 13 are prime numbers.

·         From number 13 if we subtract the sum of its digits, we get a perfect square i.e.

13 - (1 + 3) = 9 = 32

Also if the product of digits of 13 is added to it, we again a perfect square i.e.

13 + (1 x 3) = 16 = 42

Consider the equations:

132= 169

312= 961

If we insert the + sign between all the digits of above equation, the equation still holds good i.e.

(1+3)2 = 1+6 +9

(3+1)2 = 9 +6+1

·         The smallest number whose sum of digits is 13 is a perfect square i.e. 49 = 72 and 4 + 9 = 13.

·         The smallest square which contains last three digits alike is 1444. The sum of digits of this number is also 13 i.e.

1+4+ 4+ 4 = 13

·         If we place the number 13 before its reverse i.e. 31 we get the number 1331 which is a cubic number i.e. 1331= 113

·         If we take the cube of number 13 i.e. 133 = 2197 and rearrange the digits of the cube 2197 we get the famous Ramanujan's number 1729.

·         13 is the average number of the prime factors of the famous Ramanujan's number 1729. i.e.

1729 = 7 x 13 x 19

(7 + 13 + 19) ÷ 3 =13

·         Take the square of the number 13 i.e. 132 = 169. Now we see that 169 contains many perfect squares in it:

The sum of the digits of the number 169 is a perfect squares and is the square of the sum of the digits of the original number i.e.

1+6+9 = 16 = 42 =(1+3)2

Divide the number in two blocks i.e. 16 and 9. We see that both are perfect square numbers and their sum and product is a perfect square:

16 + 9 = 25 = 52

16 x 9 = 144 = 122

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)

·         Sum of the numbers from 1 to 13 gives 91 which is the smallest number which can be expressed as the sum of two cubes and also as the difference of two cubes i.e.

91 = 33 + 43

91 = 63 - 53

The reciprocal of number 13 gives

1/13 = 0.076923076923076923...