Methods for solving logic puzzles which focus on thought-free procedures that facilitate solution are discussed. Two of the procedures noted pertain to the interior of any submatrix, whereas others span several submatrices. A puzzle is presented at the conclusion as an exercise for practicing the methods promoted. (MP)

An approach to how to expand explorations of determinants is detailed that allows evaluation of the fourth order. The method is built from a close examination of the product terms found in the expansions of second- and third-order determinants. Students are provided with an experience in basic mathematical investigation. (MP)

Presents 14 distinct methods to determine the sine of the angle formed by the line segments joining one vertex of a square to the midpoints of the nonadjacent sides. Nine methods were developed by mathematics club participants preparing for mathematics competitions and the remaining five by faculty members. (MDH)

Explains that primitive living structures furnish real-world problems that are solvable using mathematics and computer-modeling techniques. (KHR)

Abstract ideas in linear algebra are illustrated at different levels of difficulty through the investigation of the solution to a well-known puzzle. Matrices are used to model the puzzle and the concepts of rank, underdetermined systems, and consistency are employed in the solution to the problem. (MDH)

Counterintuitive moments in the classroom challenge common sense and practice and can be used to help mathematics students appreciate the need to explore, reflect, and reason. Proposed are four examples involving geometry, systems of equations, and matrices as counterintuitive instances. (MDH)

Cryptography is the science that renders data unintelligible to prevent its unauthorized disclosure or modification. Presents an application of matrices used in linear transformations to illustrate a cryptographic system. An example is provided. (17 references) (MDH)

Included in this column are Star Trek, a geometric construction problem; a simplified approach to correlation using scattergrams; a calculus problem concerning second derivatives for extreme values; and a note on integration by parts. (MNS)