A die (plural "dice") is a solid with markings on each of its faces. The faces are usually all the same shape, making Platonic solids and Archimedean duals the obvious choices. The die can be "rolled" by throwing it in the air and allowing it to come to rest on one of its faces. Dice are used in many games of chance as a way of picking random numbers on which to bet, and are used in board or role-playing games to determine the number of spaces to move, results of a conflict, etc. A coin can be viewed as a degenerate 2-sided case of a die.
In 1787, Mozart wrote the measures and instructions for a musical composition dice game. The idea is to cut and paste pre-written measures of music together to create a Minuet (Chuang).
The most common type of die is a six-sided cube with the numbers 1-6 placed on the faces. The value of the roll is indicated by the number of "spots" showing on the top. For the six-sided die, opposite faces are arranged to always sum to seven. This gives two possible mirror image arrangements in which the numbers 1, 2, and 3 may be arranged in a clockwise or counterclockwise order about a corner. Commercial dice may, in fact, have either orientation. The illustrations above show 6-sided dice with counterclockwise and clockwise arrangements, respectively, when viewed from along the three-fold rotation axis towards the center of the die.
The cube has the nice property that there is an upward-pointing face opposite the bottom face from which the value of the "roll" can easily be read. This would not be true, for instance, for a tetrahedral die, which would have to be picked up and turned over to reveal the number underneath (although it could be determined by noting which number 1-4 was not visible on one of the upper three faces). The arrangement of five spots
Shapes of dice other than the usual 6-sided cube are commercially available from companies such as Dice & Games, Ltd.® Diaconis and Keller (1989) show that there exist "fair" dice other than the usual Platonic solids and duals of the Archimedean solids, where a fair die is one for which its symmetry group acts transitively on its faces (i.e., isohedra). There are 30 isohedra.
The probability of obtaining
since each possible arrangement contributes one term.
so the desired number
Expanding,
so in order to get the coefficient of
But
so
where
(Uspensky 1937, pp. 23-24).
Consider now
and
The most common roll is therefore seen to be a 7, with probability
For
and
For three six-sided dice, the most common rolls are 10 and 11, both with probability 1/8; and the least common rolls are 3 and 18, both with probability 1/216.
For four six-sided dice, the most common roll is 14, with probability 73/648; and the least common rolls are 4 and 24, both with probability 1/1296.
In general, the likeliest roll
which can be written explicitly as
For 6-sided dice, the likeliest rolls are given by
or 7, 10, 14, 17, 21, 24, 28, 31, 35, ... for
Unfortunately,
The probabilities for obtaining a given total using
Boxcars, Coin Tossing, Craps, de Méré's Problem, Efron's Dice, Isohedron, Newton-Pepys Problem, Poker, Quincunx, Sicherman Dice, Snake Eyes, Yahtzee Chuang, J. "Mozart's Musikalisches Würfelspiel." //sunsite.univie.ac.at/Mozart/dice/.Cook, K. "What Shapes do Dice Have?" //www.dicecollector.com/diceinfo_how_many_shapes.html.Culin, S. "Tjou-sa-a--Dice." §72 in Games of the Orient: Korea, China, Japan. Rutland, VT: Charles E. Tuttle, pp. 78-79, 1965.Diaconis, P. and Keller, J. B. "Fair Dice." Amer. Math. Monthly 96, 337-339, 1989.Dice & Games, Ltd. "Poly Dice & Dice for Hobby Games." //www.dice.co.uk/fs_poly.htm.Evans, D. C. "Coordinate Systems: Right and Left Handed Dice. Right?" //users.erols.com/ee/dice.htm.Gardner, M. "Dice." Ch. 18 in Mathematical Magic Show: More Puzzles, Games, Diversions, Illusions and Other Mathematical Sleight-of-Mind from Scientific American. New York: Vintage, pp. 251-262, 1978.Pegg, E. Jr. "Fair Dice." //www.mathpuzzle.com/Fairdice.htm.Pickover, C. A. The Mathematics of Oz: Mental Gymnastics from Beyond the Edge. New York: Cambridge University Press, p. 245, 2002.Robertson, L. C.; Shortt, R. M.; Landry, S. G. "Dice with Fair Sums." Amer. Math. Monthly 95, 316-328, 1988.Sloane, N. J. A. Sequence A030123 in "The On-Line Encyclopedia of Integer Sequences."Tietze, H. "Über die Anzahl der stabilen Ruhelagen eines Würfels." Elem. Math. 7, 97-100, 1948.Uspensky, J. V. Introduction to Mathematical Probability. New York: McGraw-Hill, pp. 23-24, 1937.Dice
Weisstein, Eric W. "Dice." From MathWorld--A Wolfram Web Resource. //mathworld.wolfram.com/Dice.html