If you enjoy magic squares and their unusual and fascinating numerical properties, you are in good company. Indeed, many a professional mathematician, scientist and amateur has shared the same interest. Technical research work on the properties of magic squares is available aplenty in the literature or in books concerned with the recreational aspects of mathematics. Studies of magic squares naturally lead to some elements of group theory, of lattices, of Latin squares, of partitions, of matrices, of determinants, and so on …

By definition, the general n x n magic square is a square array of n2 numbers {aij; i, j = 1,2,... , n) whose n rows, n columns, and two main diagonals have the same sum s. It is therefore natural to think of a magic square as a matrix and we shall do this in the present note, simply referring to it as a magic matrix.

This extremum problem is really a classical beauty. It has had a long and interesting history since it was formulated by Fermat in the 17th century. Given three points A, B and C, the task is to find a point P such that the sum of distances PA + PB + PC is minimal; (see Figure 1). After a few years Torricelli found the solution: P should be situated so that the angles between the half-lines PA, PB and PC are all 120° (except when one angle of the triangle ABC is greater than or equal to 120°). The solution has then been rediscovered many times in new and interesting ways.

On 6 October 1997 NASA plans to launch a space probe named Cassini which, if all goes to plan, will follow a convoluted path which will take it past Venus in April 1998 and again in June 1999 before it repasses close to Earth in August 1999. By then it will have gained enough speed to set out to more distant planets and after passing Jupiter at the end of the millennium (i.e. at the end of the year 2000) it should reach Saturn on 25 June 2004, where it will spend four years studying that planet and its satellites.

How many ways are there of making up £1 using coins? Omitting the use of the £1 coin, we are asking for the number of ways of ‘partitioning’ 100 using parts of 1, 2, 5, 10, 20, 50. For n ≥ 0, let f (n) denote the number of solutions to the equation

in non-negative integers xi, so that our required number is f (100). It is not difficult to see that f(n) is the coefficient of tn in the product Π(1 + tk + t2k +… ) over the parts k = 1, 2, 5, 10, 20, 50.

The need for clarity in the teaching of mechanics in the initial stages is vital if a firm grasp of principle is to be fostered. I had been teaching A level students about locomotion in a conventional way for some years when it occurred to me that something was basically unsound about the way in which textbooks treat the subject. At best they appear unclear and at worst they seem to flout basic principles. Examination papers mirror the textbook treatment.

There are hints of unique factorisation in Greek arithmetic. Indeed, some commentators have seen the Fundamental Theorem of Arithmetic (FTA), that the natural numbers can be expressed as products of primes in a unique way, lurking in Euclid’s Elements (c. 300BC). What can be said with certainty is that the history of the FTA is strangely obscure. It is not too much of an exaggeration to say that the result passed from being unknown to being obvious without a proof passing through the head of any mathematician.

In the High and Far-Off Times, O Best Beloved, before GCSE, frogs did not spend their days in queue-jumping investigations. Each frog sat on a lily-pad in the middle of his very own pond, wondering how to get to the edge.

Now these frogs were Progressive Frogs—more than that, O Best Beloved, they were Geometrically Progressive Frogs, and each time they jumped, they could only manage to jump half the distance of their last jump.

We will discuss in this article a fractal-like structure made from a flat piece of paper. What will motivate most people to want to make the structure is that it is pretty. In fact, the exercise has two rather obvious uses. First, greeting card companies may want to use the idea to manufacture interesting 3-dimensional cards which fit conveniently into envelopes; and, second, teachers may wish to teach students how to make it (and this process will also involve teaching them some beautiful mathematics). The structure itself is a model for a stage in a self-similarity process leading to a fractal. Building the model involves scoring a flat piece of paper in a prescribed manner, cutting along some of the score lines, and then folding some lines as ‘mountain’ folds and others as ‘valley’ folds.

In introductory courses in abstract algebra the cyclic groups Zn, the dihedral groups Dn, and the symmetric and alternating groups Sn and An, for various integers n, are often used to provide examples of various concepts. The intent of this note is to argue that another group could readily be added to this list: SL (2, 3), the multiplicative group of two by two invertible matrices of determinant 1 with entries from the field with three elements. Though this non-abelian group of order 24 does not appear often in introductory presentations, it is an excellent source of group theoretic examples and is also accessible to beginners, who at this stage of their study most likely have had some experience with matrices. Thus computations in SL (2, 3) can be implemented almost as easily as in the cyclic groups, and defining relations need not be introduced.

Much of the investigational work that pupils do in schools reduces to a routine of generating data, spotting number patterns and describing those patterns [1]. I will refer to this routine as the inductive approach. Many GCSE candidates only use algebraic notation as an alternative translation of what they have already articulated in words. Yet surely the power of algebra is in its potential for providing proof and suggesting further enquiry, based on the similarity of structure between the algebraic model and the original situation.