A numerical coincidence is an equality or near-equality between different mathematical quantities which has no known theoretical explanation. Sometimes such equalities remain mysterious and intriguing, and sometimes theory advances to the point where they can be explained and are no longer regarded as surprising.

## Posts Tagged 'Recreational Maths'

### Numerical Coincidences

Published March 23, 2017 Occasional Leave a CommentTags: Number Theory, Recreational Maths

### Topology in the Oval Office

Published February 23, 2017 Occasional Leave a CommentTags: Graph Theory, Recreational Maths, Topology

Imagine a room – the Oval Office for example – that has three electrical appliances:

• An air-conditioner ( a ) with an American plug socket ( A ),

• A boiler ( b ) with a British plug socket ( B ),

• A coffee-maker ( c ) with a Continental plug socket ( C ).

The problem is to connect each appliance to the correct socket, **avoiding any crossings of the connecting wires.**

### Metallic Means

Published February 9, 2017 Occasional Leave a CommentTags: Algebra, Arithmetic, Recreational Maths

with the value

.

There is no doubt that is significant in many biological contexts and has also been an inspiration for artists. Called the *Divine Proportion*, it was described in a book of that name by Luca Pacioli, a contemporary and friend of Leonardo da Vinci.

### That’s Maths Book Published

Published October 27, 2016 Occasional Leave a CommentTags: Recreational Maths

A book of mathematical articles, *That’s Maths*, has just been published. The collection of 100 articles includes pieces that have appeared in The Irish Times over the past few years, blog posts from this website and a number of articles that have not appeared before.

The book has been published by Gill Books and copies are available through all good booksellers in Ireland, and from major online booksellers. An E-Book is also available online.

### Recreational Mathematics is Fun

Published August 18, 2016 Irish Times Leave a CommentTags: Recreational Maths

We all love music, beautiful paintings and great literature without being trained musicians, talented artists or accomplished writers. It is the same with mathematics: we can enjoy the elegance of brilliant logical arguments and appreciate the beauty of mathematical structures and symmetries without being skilled creators of new theorems. [See TM097, or search for “thatsmaths” at irishtimes.com].

### Lateral Thinking in Mathematics

Published July 7, 2016 Irish Times Leave a CommentTags: Algorithms, Puzzles, Recreational Maths

Many problems in mathematics that appear difficult to solve turn out to be remarkably simple when looked at from a new perspective. George Pólya, a Hungarian-born mathematician, wrote a popular book, *How to Solve It*, in which he discussed the benefits of attacking problems from a variety of angles [see TM094, or search for “thatsmaths” at irishtimes.com].

### Bloom’s attempt to Square the Circle

Published June 16, 2016 Irish Times Leave a CommentTags: Geometry, Recreational Maths

The quadrature of the circle is one of the great problems posed by the ancient Greeks. This “squaring of the circle” was also an issue of particular interest to Leopold Bloom, the central character in James Joyce’s novel *Ulysses*, whom we celebrate today, Bloomsday, 16 June 2016 [see TM093, or search for “thatsmaths” at irishtimes.com].

The challenge is to construct a square with area equal to that of a given circle using only the methods of classical geometry. Thus, only a ruler and compass may be used in the construction and the process must terminate in a finite number of steps.