By Hans Rademacher

Requiring just a easy history in aircraft geometry and straightforward algebra, this vintage poses 28 difficulties that introduce the elemental principles that make arithmetic actually intriguing. "Excellent . . . a completely relaxing sampler of interesting mathematical difficulties and their solutions"—Science journal.

**Read Online or Download The Enjoyment of Mathematics: Selections from Mathematics for the Amateur (Dover Books on Mathematical and Word Recreations) PDF**

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**Extra info for The Enjoyment of Mathematics: Selections from Mathematics for the Amateur (Dover Books on Mathematical and Word Recreations)**

**Sample text**

After guessing at that digraph and then at the first word of the crypt, you may be able to solve this without further help. ) 8. The Gold Bug Cipher In 1843 Edgar Allan Poe won a $100 prize for his story “The Gold Bug,” the plot of which hinges on a mysterious cipher. The story has intrigued readers ever since. If you read the story, you were probably baffled by the cipher. No wonder. Numbers and symbols all run together— very confus ing. With minor revisions (changing certain symbols) here is the cipher as Poe presented it: 53## +305 ) )6 *; 4826 )4 #.

34; 48)4# #? ; Cipher. # + /( ) - 42 Cryptograms and Spygrams Taking a frequency count, you would write the following fre quencies over the cipher alphabet: 0 - 6 , 1 - 8 , 2 - 5 , 3 - 4 , 4 - 1 9 , 5 - 1 2 , 6 - 1 1 , 8 - 3 3 , 9 - 5 , *- 13, : —4, . - 1 , ; —26. - 3 , # - 1 6 , + - 8 , 1 -2 , ( - 1 0 , ) - 1 6 and - - 1 . The letter appearing most frequently in a sim ple substitution crypt is usually E. Looking over your frequencies, you decide which number or symbol you will try, first, for E.

Courage W A H T W C E 0 M 0 M N L C Y A L B L R A E V R Y S I N 0 T T H E A L C K F 0 F E R A B U I T T S 0 C N Q E U S T Y S D N Y E H A R R I S . ) 8. Value System F I U 0 Y A C P S N N E P A D R E C E F L T S U Y L E S S E F A R E T 0 N I N 0 Miscellaneous Types A N R E P E F L T C U Y L E S S E A M S N N Y R E U 0 V A H L E R A E E N 0 H D T W I L 0 E V. ) Cryptograms in which one letter of the alphabet consistently represents another letter are “sim ple substitution” cryptograms. Those in which the actual letters are concealed by moving them about are called “transposition” cryptograms (or ciphers).