# 13

## Monday Open Thread; November 13 is World Kindness Day

November 13 is the 317th day of the year, there are 48 days left
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Today's number is 13

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13 is
13 is a prime number, it is the 6th prime

13 is also a prime if the digits are reversed (31)

13 is a pythagorean prime (13 = 3**2 + 4**2 & 13 = 4n+1 where n =3)

## March 13, 2017 Open Thread; L Ron Hubbard's Birthday

March 13 is the 72nd day of the year. There are 293 days left.

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Today's number is 13

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13 is
13 is a prime number, it is the 6th prime

13 is a Wilson Prime (see numberphile video)

13 is also a prime if the digits are reversed (31).

February 13 is the 44th day of the year. There are 321 days left.

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Today's number is 13

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13 is
13 is a prime number, it is the 6th prime

13 is also a prime if the digits are reversed (31).

## Open Thread for June 13, Happy Lucky 13.

June 13 is the 164th day of the year, there are 201 days left in 2016

13 is a prime number, it is the 6th prime

13 is also a prime if the digits are reversed (31).

13 is a fibonacci number (0,1,1,2,3,5,8,13).

13 is the hypotenuse of a right traingle with sides of 5 & 12. 5, 12 & 13 can be used to test for right angles, like 3,4 & 5 can