JANUARY 11

                                                             JANUARY 11

Let's first begin the article with the historical events occurred on January 11.

1. On Jan 11, 1672 - Issac Newton presented his telescope to the Royal Society of London whereas he was elected the Fellow of Royal Society of London.

2. On Jan 11, 1787, William Herschel discovered the first two moon of Uranus: Titania and Oberon.

3. On Jan 11, 1775, before the Academie des Sciences, Gaspard Monge (1746–1818) presented  a memoir in which he used two planes of projection in his descriptive geometry. 

4. On Jan 11, 1935 at a conference of the Royal Astronomical Society, young astronomer Subrahmanyan Chandrasekhar presented his findings on electron degeneracy pressure and the maximum mass of a stable white dwarf star. 

                                             Mathematicians of Day 

Mathematicians born on 11th January

1545: Guidobaldo del Monte                                                  1707: Vincenzo Riccati 

1734: Achille-Pierre Dionis du Séjour                                    1825: William Spottiswoode 

1826: Giuseppe Battaglini                                                       1845: Victor Bäcklund

1938: Fischer Sheffey Black 

Mathematicians died on 11th January

1757: Louis Castel                                                                    1903: Henry Watson 

1929: Micaiah Hill                                                                    1941: Emanuel Lasker 

1946: J Watt Butters                                                                  1947: Edward Ross

1949: Torsten Carleman                                                            2002: Shanti Swarup Gupta 

2014: Zoltán Dienes                                                                  2019: Michael Atiyah 

 Facts About Number Eleven (11)

1. 11 is the only prime comprising an even number of identical digits.

2.  It is the fourth number that stays the same when written upside down. The first three are 0, 1 and 8. The others such numbers less than 100 are 69, 88, 96

 3. The first four powers of 11 yield palindromic numbers: 

                   11¹ = 11, 11² = 121, 11³ = 1331, and 11⁴ = 14641

4. 11 is the first prime exponent that does not yield a Mersenne Prim. Example , which is a composite number.

5.  A polygon with 11 sides is called - hendecagon. Using a compass and straightedge, you can't make a regular hendecagon. Moreover, it is the first polygon that can't be constructed using angle trisector.

6.  It is the fourth Sophie Germain Prime. A prime number p is a Sophie Germain prime if 2p+ 1 is also a prime. The first ten Sophie Germain primes are 2, 3, 5, 11, 23, 29, 41, 53, 83 and 89.

7.   It is a Stormer number. A Stormer number is a positive integer n for which the greatest prime factor of n² + 1 meets or exceeds 2n. It is named after Carl Stormer. The first eight Stormer numbers are 1, 2, 4, 5, 6, 9, 10, and 11.

Divisibility Test Rule of 11

Here is a link that tells you 3 methods of divisibility by 11

CLICK HERE FOR DIVISIBILITY RULE OF 11