**12**= 2

^{2}x 3.

**12**is the sum of the first three even integers and the sum of thee consecutive odd integers:

**12**= 2 + 4 + 6 = 3 + 4 + 5.

A regular dodecahedron has a regular pentagon on each of its

**12**faces.**12**has a unique representation as a sum of three squares:

**12**= 2

^{2}+ 2

^{2}+ 2

^{2}.

**12**is the number of integer partitions of 11 into distinct parts.

**12**is 22 in base 5.

There are

**12**ways to arrange eight queens on a chessboard so that no queen can capture any other queen (not counting rotations and reflections as being different). Can you find one of these chessboard arrangements?**12**is a dozen. There are

**12**months in a year and

**12**inches in a foot;

**12**o'clock is midday or midnight. There are

**12**signs of the Zodiac,

**12**apostles, and typically

**12**people in a jury.

Source: Phillips, R. 1994.

*Numbers: Facts, Figures and Fiction*. Cambridge University Press.
## 2 comments:

12: Otras representaciones

12: 5^2+12^2=13^2

12: 12^2+16^2=20^2

12: 12^2+35^2=37^2

12=2^4-2^2=3^1+3^2=4^2-4^1

12=7^3+10^3-11^3

12^2=10^3-8^3-7^3-1^3

12^3=9^3+10^3-1^3

12^5=4^5+5^5+6^5+7^5+9^5+11^5

12*12=144 y 22*21=441

2^12+2^12+3^12 es primo según

http://primes.utm.edu/curios

12*2^12-12-1 es primo segun

http://isthe.com/tech/math/primes

12+-1 es primo ya que 11 y 13 son primos.

12 es el numero atomico del magnesio

12 tiene como norma (7+2*(12)^(1/2)*(7-2*(12)^(1/2)=1 cuya representación es 7^2-12*2^2=1

12=Q^5+1/Q+1/Q^3+1/Q^6 donde Q=Phi la Divina Proporcion que tiene como valor Q=(1/2*(1+(5)^(1/2)= 1,6180339887...

Rafael Parra de Barcelona

Otras propiedades del numero 12:

12^2-4^2=2^7

12^3-4^3=13*2^7

12^4-4^4=5*2^12

12^5-4^5=11^2*2^11

12^6-4^6=7*13*2^15

12^7-4^7=1093*2^15

12^8-4^8=5*41*2^21

12^9-4^9=13*757*2^19

La expresion 5^n-12 genera una importante cantidad de primos

-7,-2,3,13,23,43,53,73,83,103,113, 163,173,193,223,233,263,283,293, 313,353,373,383,433,443,463,503, 523,563,593,613,643,653,673,683, 733, entre otros

Rafael Parra de Barcelona

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