Stories by Martin Gardner

Presenting the one and only Dr. Matrix, numerologist, in his annual performance

How to use the odd-even check for tricks and problem-solving

A mixed bag of problems, and answers to last month's board-game questions

About two new and two old mathematical board games

How to solve puzzles by graphing the rebounds of a bouncing ball

Permutations and paradoxes in combinatorial mathematics

Topological diversions, including a bottle with no inside or outside

A discussion of helical structures, from corkscrews to DNA molecules

"On reptiles, polygons that can make larger and smaller copies of themselves"

A bit of foolishness for April Fools' Day

A new paradox, and variations on it, about a man condemned to be hanged

Curves of constant width, one of which makes it possible to drill square holes

The author pays his annual visit to Dr. Matrix, the numerologist

Some simple tricks and manipulations from the ancient lore of string play

Some puzzles based on checkerboards, and answers to last month's problems

A collection of puzzles involving numbers, logic and probabilities

Tests that show whether a large numbers can be divided by a number from 2 to 12

A variety of diverting tricks collected at a fictitious convention of magicians

Fiction about life in two dimensions

The game of solitaire and some variations and transformations

Symmetry and asymmetry and the strange world of upside-down art

About three types of spiral and how to construct them

How to build a game-learning machine and then teach it to play and to win

A clutch of diverting problems, and the answers to those of last month