# 100 Numerical Games

Pierre Berloquin is a French engineer who graduated form the Ecole Nationale Supérieur des Mines, Paris in 1962. He is a freelance writer and had like Martin Gardner regular science columns in French magazines. He has a special interest in games and logic puzzles and published many books on these topics.

The present collection appeared originally around 1973, was collected and translated by Pierre Berloquin and first published in this form in 1976. It is now reproduced by Dover in 2015 together with a similar collection *100 Geometric Games*. Martin Gardner in his foreword announces this booklet as one of a collection of four, the other two dealing with logical and alphabetical puzzles as they were originally published by Charles Scribner's Sons, New York. For a copy of the latter two one should try to find an original most probably to be found in antiquarian or second hand book shops, unless Dover has plans to also republish those in the future.

Technically speaking these are puzzles, not games, so that the title can be a bit misleading. In practice, each puzzle is printed on a separate page with an illustration by Denis Dugas. Some of the drawings are just illustrative for the puzzle, like in ``How many times do the hand of a clock form a right angle in 24 hours'', but sometimes they are an essential and are part of the problem formulation as for partially filled magic squares that have to be completed. There is some repetition in the type of puzzles, like several variants of magic squares. You also see several multiplications or divisions of large numbers written out as one would perform it by hand with pencil and paper but most of the digits are replaced by stars, and one has to fill in the missing digits. Classical are also the problems where you have to give different ways to form for example some number by using only one digit, parenthesis, and standard arithmetic operations. The challenge is clearly to find the most compact form. For example 20 = 5 × 5 − 5. Another recurrent type is the following. Given a diamond shape filled up with letters or numbers and the question is how many times can a certain pattern be found along rows, columns or diagonals.

The puzzles are not very difficult so that the reader does not need any mathematical training to solve them. They are the kind of mild brain teasers that one finds in the puzzle corner of a newspaper. All the solutions are collected at the end of the booklet. An easy going puzzle book that, thanks to Dover, is saved from oblivion.

**Submitted by Adhemar Bultheel |

**16 / Nov / 2015