Dozenal divisibility tests
Daily Dozen: Thu 13 May 11EX: Dozenal has easy divisibility tests for all lower integers except 7 and X.
— Dozenal Society DSA (@dozenal) May 15, 2014
Category: number
103rd day of the year
For the 103rd day of the year: 103 is the reverse of 301. The same is true of their squares: 103² = 10609 and 301² = 90601
— jim wilder (@wilderlab) April 13, 2014
Logarithms
On the anniversary of Napier’s death here are a couple of quotes regarding his logarithms;
Briggs said
Napper, lord of Markinston, hath set my head and hands a work with his new and admirable logarithms. I hope to see him this summer, if it please God, for I never saw a book which pleased me better or made me more wonder.
and Laplace said logs
…by shortening the labours, doubled the life of the astronomer.
Read Napier’s bio.
Baron Merchiston’s death day!
John Napier (1550-1617) best known for inventing logarithms but did much more, died 4 Apr http://t.co/wNKPRtKX4P
— Maths History (@mathshistory) April 4, 2014
Cliff Pickover tweet
Scream! The string 79873884 1st occurs in Pi at position 79873884, counting from 1st digit after the decimal point. pic.twitter.com/kcASDJSV1A
— Cliff Pickover (@pickover) March 30, 2014
Incredible Numbers by Professor Ian Stewart » An iPad app to show the beauty and wonder of numbers
David Acheson of 1089 and all that
[iframe width=”100%” height=”480″ src=”http://www.youtube.com/embed/BJ7_fFABc9s”]
“…one of the key elements of mathematics, at its best, is the element of surprise.”
Plus article by David Acheson on The element of surprise in mathematics
QI tweet
ZENZIZENZIZENZIC n. The eighth power of a number. ( A word coined by Robert Recorde (c.1512-58), inventor of the = sign)
— The QI Elves (@qikipedia) March 23, 2014
Dozenal Society tweet
Daily Dozen: Sun 1E Mar 11EX: Dozenal e to four places (2;8752) varies 0;0036% from true; decimal (2.7183) varies 0;0046% from true.
— Dozenal Society DSA (@dozenal) March 23, 2014
π day special from aperiodical
Currently seeing how many digits I can remember with the help of this app Learn Pi Free