Brain Teasers
Brain Teasers
Learn to “think outside the box” with Brain Teasers, a book of mental puzzles by Kiran Srinivas! This exciting and diverse collection of mental puzzles will equip you with the valuable ability to “think outside the box.” Brain Teasers teaches creative, non-standard approaches to problem solving, and will force you to think in ways you never have before. Brain Teasers includes many interview puzzles, and if you plan to interview at an investment bank, consulting firm, high-tech firm, or
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(out of 11 reviews)
List Price: $ 9.95
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Category: Puzzles
Review by Jan Harelson for Brain Teasers
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Wow! This book is so much fun. But I am warning you that it is also very addictive so make sure that you have the time and patience. I would love to see some follow-ups since I’m almost all the way through. Thanks!!!
Review by C. Ayars for Brain Teasers
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The problem with many “brain teaser” books is that they all have many of the same questions. That is not the case with this book. The questions in this book are challenging and fun. Makes for a great book to keep at the office to break up the monotony of the work day.
Review by S. Telan for Brain Teasers
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I was excited to get this book as a gift but found that most of the puzzles have already been seen in other books that I used. There were a few new ones but probably not enough to justify buying it.
Review by Salvatore R. Mangano for Brain Teasers
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The answer to Brain Teaser #18 is incorrect. !Spoiler Alert!
The answer should be 27000001.
The problem is that all the digital sums are not 55 as the answer key suggests. For example consider the pair:
(10 – 999,990)
Here the digital sum is 46!
In fact if you break it down only 450000 of the sums are 55, 45000 of the sums are 46, 4500 are 37, 450 are 28, 45 are 19 and 4 are 10.
So the method of solution is not viable because the above would be difficult to figure out (I used a computer).
Rather the proper analysis is to show that each place value contributes 100000 of each number for 1-999,999 (e.g, there are 100000 1′s in the ones column, 100000 1′s in the tens column, and so on)
So you get
600000 * 1 + 600000 *2 … 600000 *9 =
600000 (1+2+3+4+5+6+7+8+9) =
600000 * 45 = 27,000,000
But you need to add 1 for 1,000,000
So the final answer is 27000001
This is also verified by the following Mathematica brute force program:
digitalSum[x_] := Total[Flatten[IntegerDigits[Table[i,{i,1,x}]]]]
digitalSum[1000000]
27000001
Don’t know of any other mistakes and otherwise the book is excellent!!