A card trick that can be explained and justified using first-year algebra is presented. It illustrates the power of mathematics to unmask seemingly complex situations. (MNS)

The application of the Hamilton method for apportioning seats in the United States House of Representatives is presented based on the 1980 census. It is felt that this method is preferable to the equal proportion method currently used if for no other reason than the greater appearance of fairness. (MP)

A series of problems is presented that (1) focus on certain kinds of numbers or (2) emphasize a specific concept of number theory. Several are appropriate for extensive investigation with a computer. (MNS)

The game of Yahtzee is discussed in terms of the various outcomes of turns in the game and their point values and the probabilities associated with achieving specific combinations of dice values. Several tables and methods of table construction are noted, and several challenge exercises are included. (MP)

It is seen as important that mathematics teachers encourage open, imaginative investigations that give students an opportunity to probe, find patterns and relations, and derive new patterns and relations. The article focuses on multiplication tables and classes, including questions for further exploration. (MP)

The material focuses on two posters that provide motivational problem-solving activities with money, in particular on experiences related to making change. Suggestions are given for ways to go further with the posters and extend pupil explorations. The activity posters are designed to maximize the possible answers. (MP)

The use of backward mathematics is promoted as an enrichment strategy which gives pupils the opportunity to generate creative responses that explore many possibilities. It is felt that teachers will find the instructional method a worthwhile innovation, and a technique useful in any curricular area. (MP)

A possible logical flaw based on similar triangles is discussed with the Sherlock Holmes mystery, "The Muskgrave Ritual." The possible flaw has to do with the need for two trees to have equal growth rates over a 250-year period in order for the solution presented to work. (MP)

Describes the Minnesota Talented Youth Mathematics Project for junior high school students in terms of participant selection, curriculum, teacher selection, course grades and credits, and outcomes of the project. (DS)

Two kinds of secret writing, codes and ciphers, are discussed. The weakness of a ciphering system mentioned in the March 1981 issue is pointed out, and an alternate method is presented. Programs written in BASIC are presented which can be used to encipher messages and help break ciphers. (MP)

The material is designed for student estimation of factors and divisors, with calculator use for checking estimations. Four worksheet masters are designed for classroom use. It is believed that problem-solving skills can be encouraged as students look for ways to improve on estimations. (MP)

Ways to make a discussion of the commutative properties of addition and multiplication more interesting to students are reviewed. An alternative promoted is a transposition-of-digits property, seen as useful in a number of instructional situations. The proposed investigation could be structured around calculator use. (MP)

A complete characterization of minimum conditions for congruence of quadrilaterals is presented. Convex quadrilaterals are treated first, then concave quadrilaterals are considered. A study of such minimum conditions is seen to provide some interesting and important activities for students. Only background in triangle congruence is necessary. (MP)

Presented is an edited transcript of an interview with Dr. Caleb Gattegno exploring the teaching approaches used in a film of the same name. (MP)

A discussion of the mathematics of rugby is related to an earlier article about mathematics and the physical world. (MP)