The symbols + and –, referring to addition and subtraction, first appeared in 1456 in an unpublished manuscript by the mathematician Johann Regiomontanus (a.k.a. Johann Müller). The plus symbol, as an abbreviation for the Latin et (and), was found earlier in a manuscript dated 1417; however, the downward stroke was not quite vertical.
In 1631, the multiplication symbol × was introduced by the English mathematician William Oughtred (1574–1660) in his book Keys to Mathematics, published in London. Incidentally, this Anglican minister is also famous for having invented the slide rule, which was used by generations of scientists and mathematicians. The slide rule’s doom in the mid-1970s, due to the pervasive influx of inexpensive pocket calculators, was rapid and unexpected.
Sunday, April 3, 2011
Math Quotes #4
“Mathematics, rightly viewed, possesses not only truth, but supreme beauty — a beauty cold and austere, like that of sculpture”
"In our private life as in our collective life there is no other truth than a statistical one."
“We now know that there exist true propositions which we can never formally prove. What about propositions whose proofs require arguments beyond our capabilities? What about propositions whose proofs require millions of pages?
(Bertrand Russell, Mysticism and Logic, 1918).
"In our private life as in our collective life there is no other truth than a statistical one."
-- Simone de Beauvoir
“We now know that there exist true propositions which we can never formally prove. What about propositions whose proofs require arguments beyond our capabilities? What about propositions whose proofs require millions of pages?
Or a million, million pages? Are there proofs that are possible, but beyondus?”
(Calvin Clawson, Mathematical Mysteries).
A palindromic prime formed from the reflected decimal expansion of π
314 1592653589 7932384626 4338334626 4832397985 3562951413
Friday, April 1, 2011
Letters Triangle
The letters represent different natural numbers under 100
Each letter is the sum of the two natural numbers just below it.
What is each letter if C > B?
A
B C
D E F
G H I J
K L M N O
P Q R S T U
Each letter is the sum of the two natural numbers just below it.
What is each letter if C > B?
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