Math puzzle
A math puzzle is a math- based puzzle . The mathematical facts often come from number theory or geometry .
A famous inventor of such puzzles was the American Samuel Loyd (1841–1911), who from 1870 published his puzzles in numerous newspaper columns and magazines. The player inventor Martin Gardner (1914-2010) also invented and published numerous new math puzzles. Usually such tasks are packed into a little anecdote with an exciting title so that they don't have to be explained too dryly in mathematical terms.
Various magazines, including Die Zeit , regularly publish math puzzles for the entertainment of their readers. A new type of mathematical puzzles are puzzles like Sudoku , which were made famous worldwide by the Japanese magazine Nikoli .
Types of puzzles
Geometric puzzle
Example: A farmer wants to tie up a cow in the meadow in such a way that it can eat exactly one semicircle. However, he only has three stakes and two long ropes available. How does he have to tie up the cow?
- The farmer has the pegs at the positions A , B and C take. The a cable it stretched between the pegs A and B . He attaches the second rope to the first in such a way that it can slide on it, connects it with the cow, with a length that corresponds to the radius r of the circle. The cow continues to tie the rope to peg C , again with a length that corresponds to the radius r .
Number theory puzzle
Example: The children of a village school are asked to stand in rows of three in the school yard. Since there are two children left, the teacher orders them to stand in rows of four. Again two children are left and the teacher orders them to stand in rows of five. Now it is opening. How many children are in school?
The answer can be determined using the Chinese remainder theorem to be 50 + 60 n , where n can be any whole number . Since a village school can be assumed to be small, 50 will be the answer you are looking for (but 110 would be just as correct).
Logical puzzle
Example: Martin and Manfred are identical twins. One of them always lies, the other always tells the truth. You now meet exactly one of the two.
- What question do you have to ask to find out which of the two is the liar?
- What question do you have to ask to find out which of the two twins you have in front of you?
The logician Raymond Smullyan is a master at writing this type of puzzle and has published several puzzle books. The so-called zebra puzzle (also known as Einstein's puzzle ) occupied the British and American readership of a magazine for months in 1963.
See also: Logical , International Math and Logic Games Championship
Symbol puzzles and alphametics
A special form of the mathematical puzzle is the symbol puzzle or alphametics, in which the aim is to reconstruct an equation in which the digits have been replaced by symbols or letters. Usually, each digit is represented by only one symbol, and the first symbol of a number cannot stand for 0.
A symbol puzzle could look like this:
ACE + DAC = JFD - + - AAA - HFC = GI = = = AH + III = JBJ
The letters must be replaced by numbers in such a way that all equations are fulfilled horizontally and vertically. Alphametics can also be entertaining if the letters also form words. Probably the best known example of this is
SEND + MORE ------ MONEY
which, according to legend, was sent by a student to his father. The question now is how much "MONEY" is.
- 9567 + 1085 = 10652
- or with M = 0: 8542 + 915 = 9457
There are also such alphametics in German. Here is a multiplicative, especially for Wikipedia:
ESSAY * WERK = WIKIPEDIA
Multiplicative alphametics are often supplied with the written multiplication as well, to make the solution easier; occasionally, so that it is clear at all:
ESSAY * WERK
------------
KPYPIY
RSERPY
WIWKPA
YYISIA
------------
WIKIPEDIA
- 92205 * 7986 = 736349130
- Here are the intermediate results of the written multiplication:
- 645435; 829845; 737640; 553230
- See also: picture puzzle , goat problem
Arithmetic puzzle
Example for children: 5 numbers between 1 and 9 are linked using the basic arithmetic operations , whereby the result and, depending on the level of difficulty, a different number of numbers are given in changing patterns. The numbers to be inserted (framed fields) must not appear twice. The result and the individual subtotals are always whole numbers and positive. The example is suitable for students from the 2nd grade. See also Miss Lupun .
Example for adults: The same puzzle principle is increased to 9 numbers, but point calculation does not apply before line calculation . Logic can be used to limit the number of possible combinations (what subtotals are divisible by the number X?), But the focus of these puzzles is on mental arithmetic.
Another well-known arithmetic puzzle is the “ four fours ” puzzle , in which the aim is to represent given numbers with four fours.
Solution of the riddle for children: 
Solution for the big example: 
More puzzles
literature
- Sam Loyd , Martin Gardner (Ed.): Mathematical puzzles and games . 3rd edition DuMont, Cologne 2004, ISBN 3-8321-7359-5
- Raymond Smullyan: What is this book (English. What is the name of this book ). Vieweg, Braunschweig and Wiesbaden 1981, ISBN 3-528-08436-7
- Raymond Smullyan: Alice in the Rätselland (English Alice in the Puzzle Land ). 2nd edition Fischer, Frankfurt am Main 1989, ISBN 3-596-28701-4
- Raymond Smullyan: Lady or Tiger (Engl. The Lady or the Tiger ). 3rd edition Fischer, Frankfurt am Main 1987, ISBN 3-596-28176-8
- Raymond Smullyan: Mockingbirds and other meta birds (English To Mock a Mockingbird ). Fischer, Frankfurt am Main 1989, ISBN 3-596-28712-X
- Raymond Smullyan: Logic Knights and Other Villains (English Forever undecided. A puzzle Guide to Gödel ). Fischer, Frankfurt am Main 1991, ISBN 3-596-10349-5
- Raymond Smullyan: Satan, Cantor and Infinity , Insel, Frankfurt am Main 1997, ISBN 3-458-33599-4