4 comments about Speedsolving the Cube: Easy-to-Follow, Step-by-Step Instructions for Many Popular 3-D Puzzles.

1. I think this book is very well written. Dan Harris clearly knows his way around a Rubik's cube. My favorite part of the book was the section on the history of the cube and the stats.
   
   Even though the book is good, it is difficult to solve the cube without actually seeing someone do it. I learned how to solve the Rubik's cube from a YouTube video by Dan Brown. I think his YouTube user name is Pogobot.
   
   Brandon Simpson



2. I taught myself much of the methodology outlined in this book by scrounging around the Internet for various algorithms, etc. Dan Harris' website ([...]) was instrumental in teaching me how to plan ahead, and he's used his skills at creating written tutorials for a very hands-on hobby to write an excellent book.
   
   This book has several advantages over the way that most of us have had to learn our way around the cube. First, it's laid out in a linear fashion, so ideas are introduced to the reader in a very organized way, interspersed with lots of examples. Second, through the format of a published book, a comprehensive set of the many algorithms needed for a complete speedsolving solution are presented in a bound paper copy. This is perfect for someone who wants to carry the book and a cube in their backpack or messenger bag and keep notes about which algorithms are most comfortable, which have been committed to memory, etc. I bought this book specifically for Dan's great presentation of the last layer orientation algorithms, which I have yet to learn. Having all of the algorithms organized in such a thoughtful way, in a medium that I can easily carry with me is exactly what I've needed.
   
   Great work, Dan!



3. This book seems best suited to people who already know how to solve the cube and who would like to find out how to improve their solutions. In my case, I hit a wall with my homebrew solution at about 60 seconds. While 1 minute solves are nice, it's not impressive in a world where a 20 second solve is not terribly competitive. This book seems to have the solution for that. It's too early to claim success, but what I've worked through so far is very good.
   
   Would this book be suitable for a cubing novice? That's a tough call. The book does start from scratch teaching a basic solution, but I feel other resources online are a little clearer for the absolute beginner. However, a dedicated learner could work entirely from the book. Just keep in mind that pace is very quick, and the author doesn't do that much hand holding.
   
   Would this book be suitable for an experienced speed cuber? That's hard to say, since I'm not in that category. If you follow another solving system, the book should be a very easy introduction to the authors strategy. I suspect that no matter where you are, you'll get a few new algorithms and tricks. There's also the 2x2x2, 4x4x4 and 5x5x5 solutions, which ought to provide additional value to the hardcore cuber.
   
   This book is deceptively short. Although it weighs in at barely 160 pages, there's really a lot of content if you work through the material. It's taken a week to work through the first 50 pages, and that's just the intro material. I suspect it will be months, if not years, before I've even come close to exhausting what the book has to offer. In that regard, it's a tremendous value, and I can wholeheartedly recommend the book.



4. I had tried to learn the so-called "speed cubing" methods online and had been completely frustrated. Dan Harris lays it all out perfectly: it is very easy to follow and understand. That doesn't mean that the technique is all that easy to learn: with a massive amount of algorithms to memorize it will certainly be an undertaking of some months before you can claim complete mastery of the CFOP method.
   The sections on the 2x2, 4x4, and 5x5 cubes are also very easy to follow. There is one typo that I found in the 5x5 chapter. The algorithms in Table 8.3, p125 are wrong: they are written (R r) U (R' r') U (R r) (U2 u2) (R' r') (R r) and (R2 r2) U (R2 r2) U (R2 r2) (U2 u2) (R2 r2). I spent a frustrating 10 minutes trying to figure out why I couldn't complete the centers. I found that the correct algoritms are (R r) U (R' r') U (R r) U2 (R' r') and (R2 r2) U (R2 r2) U (R2 r2) U2 (R2 r2).
   At the end of the book there is also a chapter that has algorithms for all sorts of cool patterns that can be applied to an already finished cube.
   This is a great book and no true Rubik's fanatic should be without it!

1 comments about Making Mathematics with Needlework: Ten Papers and Ten Projects.

1. Knowledgeably compiled and deftly co-edited by Sarah-Marie Belcastro (Co-Director, Hamshire College Summer Studies in mathematics and Visiting Assistant Professor of Mathematics at Smith College) and Carolyn Yackel (Mathematics Instructor, Mercer University), "Making Mathematics With Needlework: Ten Papers And Ten Projects" is unique in that it combines mathematics papers with fiber arts project instructions. Each chapter showcases a particular project and that project features sections on mathematics and mathematics education along with detailed instructions for completing the needlecraft project. The featured projects include a Quilted Mobius Band (making a mobius quilt); Diphantine Equations (making a bi-directional hat); Sierpinski Variatins (making a Sierpinski shawl); a Two Knit Stiches Tours; Symmetry Patterns in Cross-Stitch; Algebraic Structure (making algebraic socks); Fortunatus's Purse; (K)Not Cables and Braids (making a pillow of Braid Equivalence); The Graph Theory of Blackwork Embroidery (embroidering a Holbeinian Graph); and making Hyperbolic Pants. Profusely illustrated, the text is fully accessible to non-specialist general readers with an interest in needlecraft, in the mathematics underlying needlecraft, as well as having a very special attraction for math students and fiber art enthusiasts alike.

5 comments about The Colossal Book of Short Puzzles and Problems.

1. The Colossal Book of Short Puzzles and Problems is going to be THE gift to send to your puzzle-loving friends and family. Gardener is a master and a national treasure. Every math teacher should own this book as a resource, and every puzzle-lover should have it for hours of fun.
   
   Deborah Bennett, author of Randomness and Logic Made Easy



2. What a great collection of puzzles. Anyone who likes puzzles SHOULD own this.
   I initially bought this for myself. But my brother-in-law loved it so much (when it arrived) that I gave it to him as a present. Just ordered it for myself again!



3. Martin Gardner is the name that always comes to mind when one thinks of Mathematical Recreations. Anyone who ever read Scientific American magazine will remember his column in every issue. He wrote the column for 25 years;and made puzzle lovers of millions of readers. His fans ran the gamut from those with a very elementary background in mathematics to those with a high degree of knowledge. What he did was to make mathematics something to enjoy and use as a recreational pursuit. Over the years, he wrote about 70 books,many that have been popular for a long time.
   In this book, he has chosen 340 puzzles from his columns of over 25 years. He has selected simple problems as well as medium and difficult. Each problem is supplied with an answer or solution . Often, answers in puzzle books are sketchy;but here we not only get an answer but also a good idea and explanation on arriving at the solution.
   The most interesting thing about this book is that it is geared to all levels of puzzle solvers (OMNIHEURISTS). I am sure that someone who has worked only a few puzzles,and who hasn't,will find many quite easy and in a short time will progress to those with more challenge; due particularly to the answer explanations.At the same time ,those with a lot of experience will find plenty to amuse themselves.
   Along with a pick of some of the best of the columns over the years,Gardner has included 12 of the best brainteasers to have come his way since he stopped writing the column in 1986.
   Also, we are given a list of all the other books that Martin Gardner wrote over the years. Along with that, there is a list of selected titles for those interested in more in the world of Recreational Mathematics.
   If you like Mathematical Recreations or puzzles of any kind ;take a look at this book and you'll surely want to own it.



4. Great collection of thought puzzles, some well known, some highly original.
   
   What I like most is that every problem, from the simplest up to the really difficult, has a twist to it: You may think you immediately see the answer, but there is always something you didn't think of. For example Problem 1.1 (to be seen in the Excerpt when you click on the image of the book): How many dates in a year can be confusing if you don't know whether they are in European notation (28/2/2007) or US (2/28/2007)? Your first thought is "That's easy, just 12x12", until you think a second time.
   
   If you want to train your brain, solve a few of Martin Gardner's puzzles every day. Or just do it to have fun.



5. This is a superb collection of puzzles of all kinds. Anyone experienced or not in the puzzle field should own this book.
   
   Martin Gardner is a guarantee for this book's efficiency, and highly educational and entertaining content. 5/5

3 comments about Masters Kakuro: 172 Challenging Puzzles (Kakuro).

1. This book has puzzles difficult enough to be challenging without having to resort to looking up the answers. BUT! The numbers are small, skinny, and white, on a medium gray background and very hard to read. As with most kakuro books, the puzzles are way too small. Enlarge 40% and darken the background, and you're set to go. To me, it has been worth it due to the quality of the puzzles.



2. I had little difficulty reading the puzzles (per the previous reviewer), and found the puzzles themselves large enough to easily work with (compared to many others). They range from difficult to nearly impossible, but somehow I managed to make my way through the entire collection. Overall, I found the puzzles fully enjoyable; this was a collection I always enjoyed pulling out for some mental gymnastics. I wish Bumgardner would come out with a Volume II, as he has a good sense of Kakuro style--puzzles that make you think, but not necessarily (compared with, say, the Dell collections) make you have to work more than think.



3. Not a bad collection of puzzles, but as a previous reviewer said, the puzzles are very difficult to read. Mensa Kakuro is much better if you're looking for tough puzzles - better puzzles and easier to read. The Everything Kakuro Challenge Book by Timmerman is the best collection, the best puzzles I've ever done. All of them are on par with the best Dell Cross Sums, which I've been doing for over 25 years,

5 comments about The Man Who Counted: A Collection of Mathematical Adventures.

1. I absolutely loved this book! If I could afford it, I would be doling this out to my numerous young relatives at all gift-giving festivities. It is a good introduction for young people (and not so young)to mathematical curiosities such as magic squares, as well as probability and logic. Did you know that "diabolical" has another meaning?
   
   It is also very, very good literary-wise. It is written in a style reminiscent of the 1001 Arabian Nights in that it has stories within a story within a story.
   
   The sub-title "A Collection of Mathematical Adventures" belies the depth of the book. Beremiz Samir, the Calculator, does not just teach us number-crunching tricks, he also imparts to the reader a deep sense of equity (e.g. in the story about the division of bread, although through calculation he should have been compensated more, through compassion he shared equally) and social justice (e.g. read the story about halving a prisoner's life sentence).
   
   At the end of the book, upon Beremiz Samir's marriage, the "author" aptly concludes that the best solution Beremiz found was not in mathematics, but in life and love.
   
   My one sole grievance, as suggested by the title of this review, is that there are hints that the book was not written by an Arab Muslim and is 'obviously fake'. For example, in the introductory page, the "author" dates his introduction as 19 Ramadan 1321. If he was truly an Arab Muslim, he would have used the Hijri calendar year and written it 19 Ramadan 720.
   Also, in one passage relating how cosmopolitan Baghdad was in the 13th century, reference is made to the Mohammedan, Jewish and Christian inhabitants. A Muslim would never refer to himself or his co-religionists as Mohammedan, but simply Muslim. It is, however, remarkably accurate elsewhere - like the number of times Jesus in mentioned in the Quran.
   
   Though I would personally be glad if the minor hiccups would be edited off in the future, they are of relative insignificance. This book is a must-have!



2. My 9 year old has great marks in math, but neither she nor I got much past the first chapter. The writing is complex and the stories of interest only to those who love number puzzles. My 13 year old boy was far more interested in this book. If your child is younger and they aren't fascinated by numerical puzzles, give it a miss.



3. A very entertaining novel, with a collection of mathematical problems embedded, that are solved with ingenuity rather than elaborate mathematical equations. A must read for all ages.



4. This is one of the quirkiest books I've read. If you are one to hit the papers first thing in the morning to solve Sudoku, Kakuro, Mind bender, then go ahead and read this book. This is definitely your kind of book.
   
   The Man Who Counted is about a mathematician Beremiz Samir and how he solves different problems with his knowledge of mathematics. Sort of like your Arabian Sherlock Holmes, just that the problems may not be that gory in nature. More like fights over camel distribution and such. He is not your regular human calculator, rather someone who sees romance in mathematics just as he sees it in nature, poetry. It is a collection of logical puzzles, stories, observations, anecdotes. The stories are written by Malba Tahan in the manner of storytellers of old.
   
   The quirkiness doesn't end there. Malba Tahan is a fictitious person. The book is really written by a Brazilian mathematics professor, Júlio César de Mello e Souza's. This isn't just your regular pseudonym, Julio Cesar created a complete persona of an Arabic traveler Malba Tahan and wrote the books completely from his perspective.
   
   The book uses interesting fables like dividing inheritance of camels amongst brothers to show how seemingly complex mathematics can be so simple and used in ordinary things. I think it can be a good tool for teachers, when mathematics becomes a chore for kids, to them the "cool" aspect of mathematics.
   
   For those who enjoy solving logic puzzles, or even those wondering the point of Microsoft interview questions, this will be a good read. The problems may not seem like much, but the combination of storytelling with mathematics is an amusing read.
   
   [...]



5. This booke is a excelent source of entreteriment, matematical curiosities and knologe! I a must for everyone...

3 comments about Nonplussed!: Mathematical Proof of Implausible Ideas.

1. The book of Julian Havil is certainly not easy reading. Perhaps I am a dummy, but at several pages I had to read over a paragraph several times before understanding its real meaning, but the result was always worth the trouble. The calculations itself are explained thoroughly and his way of highlighting different sidesteps are often eye-openers.
   People loving Martin Gardner's articles in Scientific American, will certainly appreciate this book.



2. This book is a valuable addition to a math-puzzler's library, but contains some flaws on real-world data.
   
   For example, Havil shows, with impeccable mathematics, that if a given player has over 91.9643...% probability of winning any given point on his or her serve, that he or she has a higher likelihood of winning at the start of the game than when the score is 30-15 or 40-30. He uses this fact to back up a claim that "a high quality tennis player serving at 40-30 or 30-15 to an equal opponent has less chance of winning the game than at its start." Again, this is predicated on that 92% or better percentage of winning any given point. But in real life, high quality tennis players, even when serving, against an equal opponent does not have this high a percentage of the points gained. Take 92% as the percentage. That would mean that over 70% of the time, the non-server would not even get one point (score of 15) during a given game. If anyone watches Wimbledon or the U.S. Open, one sees that such occurrences are rare, not common. As even Havil points out, it also implies that the server will win at least 99.9% of the games. But in high-level play, set scores of 6-3, 6-4, etc. are common. With 99.9% of the games being won by the server, 99.4% of sets would go into tie-break. That's clearly not the case in the real world. But this discrepancy is needed in order to make the "paradox" that creates the "nonplussed" reaction.
   
   In the chapter on the calendar, Havil explains why the Christian feast commemorating Jesus' ascension into Heaven never falls on a Sunday by claiming that that feast is also called Holy Thursday. It's not. It's Ascension Thursday. Holy Thursday, 42 days (six weeks) before Ascension Thursday, is the day before Good Friday, and commemorates the Last Supper.



3. This book will delight readers who like to get their hands into their math. Havil sticks to mostly elementary concepts, avoiding highly abstract fields that would lose most readers. When a subject could go too far afield, Havil warns about it and presents only the part the reader needs to know, citing original source references for the interested reader. He gives complete, understandable proofs of some startling statements--proofs that leave you understanding exactly how you got there. The great thing is that you can choose to work through these problems for yourself, verifying each step, or you can just follow along with his proofs and take on faith any simple algebraic rearrangements that he may have skipped over. Compared to Havil's earlier classic on Euler's Gamma Function, this one's a bit easier to read, with numerous short sections on a variety of topics.
   
   One minor complaint is that I found some typesetting errors. One, ironically, occurs on page 49 where he uses the notation "!n" (the number of derangements of n objects) when actually he meant "n!" (the number of permutations of n objects). It's ironic because only two paragraphs later Havil warns that !n can be easily confused with n!, whereupon he adopts a new notation for !n. In the delightfully bizarre but challenging chapter on John Conway's Fractran, there are a few typos that might confuse that minority of readers who will actually try to go line-by-line through the explanation of the Fractran machine (p. 172), but if you're one of those people, discovering the errors will anyway prove your mastery.

3 comments about Black Belt Kakuro: 150 Puzzles (Martial Arts Kakuro).

1. This is the fourth in a series of Kakuro books, and the hardest. The puzzles are indeed tough, and I often had to look up the answers to figure out what I had done wrong, or to get a cell number to keep me going, but they were solvable for the most part.
   
   I also purchased the Green Belt (not-so-easy) and Brown Belt (hard) books. Conceptis Puzzles did a good job of sorting the puzzles by level of difficulty. I started with the Black Belt, as it was the first one available on Amazon. I recommend you start with an easier edition and work your way up. The puzzles are the same size in all the books, 12 columns by 21 rows, which is a good value.
   
   My only complaint is that the gimme's (two number combinations with only one answer) are repetitive. For example, for a six figure 38, the 3 almost always comes from a 5, while the 5 comes from a 6. Otherwise, there is a good amount of variety among the puzzles.



2. Most Kakuro books that claim to be advanced just aren't challenging enough for the expert puzzle solver. Most are downright easy. In fact, Black Belt Kakuro is really in a class by itself, the only consistently challenging book I've found for advanced Kakuro enthusiasts. Each of these puzzles will have you tearing your hair out -- and then rejoicing when you finally crack it. My only problem with this book is that there just isn't enough of it! The Sudoku books of this series have gone on to "second-degree" editions. When do we get Second-Degree Black Belt Kakuro??? Bring it on!



3. The puzzles in this book are fun to solve. They are very challenging and take quite a bit of brain power to solve. The puzzles are large with 6-9 number strings rather than relying on typical combinations. Solve at your own risk.

5 comments about The Adventures of Penrose the Mathematical Cat.

1. Hi I'm a Pima Community College student and, I read the book to a friend's daughter for homework. She loved the book because it was a cat doing and solving math. The book had a lot of short stories about Penrose doing math. Some of the topics she didn't get but, that was because, she was not to that level of math in school.



2. This book is a good resource for teachers! It is full of fun, interesting, and relatively simple activities that make abstract mathematical concepts come to life. Math is made less intimidating, because the mystery behind it is revealed by a curious cat with whom children can relate. The book takes mathematical concepts that might otherwise be too complex for children to grasp and simplifies them, making them more "kid friendly." Younger children, who are more likely to enjoy the cat's stories, may not fully appreciate the mathematical content. They will, however, benefit from the books pleasant introduction to mathematical concepts. Similarly, older children, who are more likely to fully appreciate the mathematical content, may not enjoy Penrose as much (or at least they might not admit that they do). However, learning with Penrose will still make the experience less intimidating. The book is clever and a great tool for teaching math, while easing and/or preventing math phobia. I will definitely use this book in my own classroom!



3. This book is a great resource for teachers! It is full of fun, interesting, and easy activities that really help its abstract mathematical concepts come to life. The book takes concepts that might otherwise be hard to grasp in their complexity and simplifies them, making them more "kid friendly." Learning from and with a cat, who is just as curious as they are, also helps make things less intimidating for children who are slightly math phobic. I will definitely be using this book in my own classroom!



4. My son really enjoyed this book for its interesting presentation of math.. he even named a cat puppet after Penrose.



5. This book is so much fun. It has mathematical concepts I had never even heard of. For someone who lost their love of math through public school, I thoroughly enjoy reading the fun ideas presented here. It makes higher math skills available to non-math people without being threatening or overwhelming. I love this book.

5 comments about Killer Sudoku 1: The Deadly New Dimension.

1. In my opinion, Killer Sudoku puzzles are much more fun and satisfying to solve than regular Sudoku puzzles because of the added complexity of the sums and the various techniques that can be employed to solve them. "Killer Su Doku 1: The Deadly New Dimension" contains 110 puzzles of which there are 17 Gentle, 30 Moderate, 42 Tricky, 16 Tough, and 5 Deadly puzzles. Each puzzle has a suggested time to beat. There is also a two-page "Guidelines for Solving Killer Su Doku".
   
   I didn't find the guidelines for solving to be particularly useful. They give a quite minimal explanation of how to solve these types of puzzles and leave out explanations of some of the more important techniques for solving, such as the 45 Rule. (Steve Arons book, "The Official Book of Killer Sudoku" contains a much more comprehensive introduction.)
   
   Regarding the suggested times, I didn't specifically time myself, but I often noticed that I took much less or much more time than what was suggested. As for difficulty, I found that sometimes a puzzle in a given section was either much harder or much easier than what was implied. The puzzles in the Deadly section were no more difficult than the ones in the Tough section. The hardest puzzles in the book are 78, 98, and 105. I eventually figured out some interesting equations and relational techniques for solving 78 and 98. (Whew, that was fun!) Puzzle 105 is the only one that I have not yet managed to solve.
   
   This brings me to a recommendation for the Solutions section. In general, I find the solutions in the backs of Sudoku books to be useless. If I finish a puzzle and it conforms to the rules then it's correct; otherwise it's wrong. I don't need a solution to tell me that. The only time I look at the solution is occasionally when I'm doing a really difficult puzzle and I want to check an intermediate result to make sure I'm on the right track so I don't end up having to erase the entire puzzle and start over. This also helps to instantly understand what type of mistake I made. Something that would be really helpful in the solutions for the really difficult puzzles would be to show a partially solved grid and an explanation of how to get to the next step.
   
   On the whole I found this book to be very enjoyable and highly recommend it for any Killer Sudoku fan. Publisher, another one please!



2. I do enjoy regular Sudoku. But there are a couple of problems with it. First, while it uses numbers, it in no way uses the properties of numbers. Second, the level of effort to solve such puzzles is generally uneven; you may get a few numbers early, but then it gets very tough, and soon after that it is easy again. When it is tough, you may have to write down possible values in a square or guess, and that's unsatisfying compared to being able to simply write down correct numbers in blank squares.
   
   With Killer Sudoku, one does get to use the additive properties of numbers, so there really is a difference between the symbols! And the level of effort is more nearly even. In addition, even hard puzzles generally can be solved without writing anything down but the answers. It is my favorite Sudoku variant ("Greater than Killer Sudoku" is my second favorite).
   
   This book is about at the right level. Do not be scared by the "deadly" puzzles at the end, as I found them to be easier than some of the earlier ones.
   
   I recommend this book to all those who enjoy a challenge and have some time on their hands.



3. If your bored of Sudoku and not finding the standard puzzles challenging you need to try these out. The page layout of this book is good there is ample room to write your number combinations and there are suggested times for each puzzle. The paper used in the book is softer but stands up fine to an eraser.



4. I ran into Killer Sudoku accidentally, and became hooked ever since. The (simple addition and subtraction) math involved adds a new dimension to the puzzle. Unlike the standard Sudoku, Killer Sudoku puzzles have more twists and surprises waiting to be explored. The more difficult puzzles in this book are very satisfactory in harboring many pleasant and exciting ones.
   
   The books contain 110 puzzles of 5 levels. When you advance to the last two level, your skill and fun are elevated as well. I guess after you mastered the game, you may want to get books with only difficult ones (and they should be so published). One nice thing about this book is that the puzzles seem to have been tested, and there is a 'par' time for each one of them. For easy one the pars are ten to 20 minutes, and the hardest ones up to 90 minutes. These par times are pretty good in that I tended to exceed them in the beginning, but after I have advanced to high levels and came back to do some easier ones that I skipped I often beat the par. The time competition factor also is a way to enjoy the easy ones.
   
   Highly recommended for going through the levels and mastering the game. If you are looking only for tough Killer Sudoku books, this one contains about 20 very good ones.



5. I encountered Killer Sudoku in a Will Shortz sudoku variants book and became hooked on it, and this is a great book of it. It allows you to move between a variety of solving techniques taken from both regular Sudoku and Kakuro. The puzzles here come in a good variety of solving difficulty, with enough easy ones for you to practice your techniques on, and enough challenging ones that you won't get bored.

5 comments about My Best Mathematical and Logic Puzzles (Math & Logic Puzzles).

1. Marvelous book. I found it better than many books but my friends, who were not that conversant with intermediate mathematics did not like it much. Though this book doesn't require a knowledge of calculus, people who have this level might appreciate the book more. But it has more to do with mathematical 'thinking' rather than mathematics itself.

   So get this one if you are good at mathematical thinking and want to challenge yourself. If you are weak in math and would rather read puzzles that require only logic, cleverness, and lateral thinking only, this may not be the one for you.




2. Martin Gardner is the grand old man of puzzles and recreational mathematics. I recommend this book for intermediary and advanced puzzle enthusiasts - beginners might find some of these too challenging.

   Intermediary puzzlists will find the pleasures of often working at the upper edge of their skills. The solutions at the end of the book are complete enough so that even those who didn't get it right the first time will get aha insights.

   The book is well worth its price even for puzzle enthusiasts. Even I knew many of the puzzles beforehand - classics indeed - but the notes in the solutions often add a twist, a clever solution or a human interest point of view.

   The age recommendation of amazon.com - 4-8 years - is probably either an insider joke or a typo. I'd recommend this book to people between 14-80 years of age, and even over.




3. "My best mathematical and logic puzzles" presents 70 of the best of the brain teaser that Martin Gardner published over a period of 25 years in his Mathematical games column at Scientific American. It some cases references to new developments related with specific puzzles have been added.
   
   Martin Gardner was always especially careful to present in his American Scientific column only new and unfamiliar puzzles that have not been included in classic collections before. Now you can challenge your solving skills and rattle your ego with a compilation of his best mind-benders.
   
   Here is an example of what you can find inside this book (31. The absent-minded teller}:
   
   "An absent-minded bank teller switched the dollars and cents when he cashed a check for Mr. Brown, giving him dollars instead of cents, and cents instead of dollars. After buying a five-cent newspaper, Mr. Brown discovered that he had left exactly twice as much as his original check. What was the amount of the check?"
   
   One of the best things about Martin Gardner books is that a carefully explained solution follows each problem, this way you learn and add new abilities to your problem solving skills, that will sure be helpful in solving real life problems, while entertaining yourself with a good and challenging reading.



4. Nice collection of puzzles with varying difficulties, which do not require any special knowledge of mathematics.



5. Very nice. I like the old-fashioned approach (I think the author has been writing books like this since the 1960s) and the problems are interesting and varied; most of them you can do in your head (hence an ideal "bathroom book") but some do make you break out the pencil and paper just to double-check. Highly recommended for interested people who studied Maths to around age 18 or beyond.