PREFACE v

Part One

MATHEMATICAL PUZZLES

I. EASY ARITHMETICAL PUZZLES .... 3

II. PUZZLES OF INFERENCE AND

INTERPRETATION 11

III. ALGEBRAIC PUZZLES—GROUP ONE 20

IV. ALGEBRAIC PUZZLES—GROUP TWO 30

V. DISSECTION OF PLANE FIGURES.. 40

VI. GEOMETRICAL PUZZLES 54

VII. PROPERTIES OF DIGITS 67

VIII. PUZZLES ABOUT INTEGERS 79

IX. DECIMATION PUZZLES 94

X. PERMUTATIONS AND COMBINATIONS . 98

XI. PROBLEMS OF PROBABILITY 109

XII. NUMBER GAMES 115

XIII. BOARD GAMES .. 120

Part Two

SOLUTIONS

SOLUTIONS AND ANSWERS TO THE

PUZZLES IN PART ONE 139

APPENDIX

HOW TO EXTRACT SQUARE ROOT 236

HOW TO EXTRACT CUBE ROOT 238

TABLE OF SQUARE ROOTS 239

TABLE OF POWERS OF 2 . 239

TABLE OF SQUARE NUMBERS 24O

TABLE OF PRIME NUMBERS 241

TABLE OF TRIANGULAR NUMBERS 242

GLOSSARY 243

This is a delightful collection of head-scratchers all described in an easy-going format. Puzzles (all of them are word puzzles, and all answers appear at the back) are grouped as algebraic, geometric, easy-arithmetical, combinatoric, puzzles about integers, etc.; none are trivial, some are extremely challenging, and they all teach some point about inference or mathematical method. In the preface, the author writes, "Some of these puzzles are old favorites... to solve many of the puzzles, you need no knowledge of mathematics other than simple arithmetic... the full method of solution is explained for the more difficult puzzles."

Great, great, great for taking an entertaining tour in mathematics and gaining some problem-solving wisdom along the way. When you solve any of these, you'll really feel ingenious. Thank you, Mr. Mott-Smith!