Importance of 20

Twenty (20)

1.      It can be expressed as the sum of first four even numbers.                                                              

  20 = 2 + 4 + 6 + 8

2.      A polygon having 20 sides is called Icosahedron. An Icosahedron is a solid with equilateral triangles on each side of its 20 faces.                              

                                             

          

3.      It is the sum of first six Fibonacci numbers.                       

                                                                20 = 1 + 1 + 2 + 3 + 5 + 8

4.      Magical triangle with numbers from 1 to 9 can be constructed with its magical constant as 20.

                                                                                                                                     

5.      The Mayans had a base 20 counting system, subdivided into base 20.

6.   It can be partioned in 627 ways

7.      Base 20 numeral system is called Vigesimal system.

8.      It can be written as the product of a squared prime and a prime.                                                      

              20 = 2² x 5

9.      It is a tetrahedral number.                                        

                                                                                       

10.  The atomic number of Calcium is 20.

11.  After 19, it is the only number with more than one digit that can be written on base 2 to base 20 using only the digits from 0 to 9.

12.  It is the second semi perfect number because it is the sum of some of its own factors.              20 = 1 + 4 + 5 + 10

13. The 20th palindromic prime (929) has a digit sum  ( 9 + 2 + 9 = 20 ) of 20.

14. It is the sum of first four triangular number

                                   20 = 1 + 3 + 6 + 10 
15. It is a self number
   ( Read more about self number on 
http://numberbyrajeshkumarthakur.blogspot.in/2018/01/self-number.html )

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Rajesh Kumar Thakur

rkthakur1974@gmail.com