Introduce Brain Teaser Basic

Lecture Notes

Solving brain teasers is not only fun but also useful for securing a good job. Many highly paid companies, such as technology firms and consultancies, use brain teasers during their interviews. This approach is favored because brain teasers offer a unique way to assess a person's ability to observe carefully, think creatively, and analyze systematically—all traits that are highly desirable in a real business environment.

Almost all brain teasers do not require in-depth subject matter expertise, underscoring their effectiveness in providing a level playing field for individuals from diverse backgrounds. The first example below serves as a classic illustration of this principle.

It is also critical to understand that brain teasers usually do not involve complex calculations. Therefore, approaching the second example below as a math problem would be a mistake.

That being said, some brain teasers, especially those used during interviews, may build upon certain subject matter knowledge. However, the key distinction between such a brain teaser and a school exam is that the solution relies more on principles rather than on specific techniques or theorems. For instance, the third example below is derived from information encryption, an important subject in modern computer science. Yet, a person without a background in computer science can also solve this problem, emphasizing the earlier point that brain teasers provide an impartial platform for interviewing candidates with different backgrounds.

This course will focus on brain teasers with a mathematical foundation. For a broader coverage, please refer to the book  Brain Teaser .



$\textbf{Bus Direction}$

Which way is this moving bus going?


$\textbf{Unique Number}$

What makes the number $8549176320$ unique?


$\textbf{Secured Delivery}$

John wants to send a valuable gift to Mary. He has a lockable box that is large enough to contain the gift. The box also has a locking ring that can have a few locks attached. However, Mary does not have the key to any of John's locks. How can John send the gift to Mary securely?

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Brain teasers emphasize problem-solving skills rather than specific subject matter knowledge, making the book  Art of Thinking  highly relevant as well. Many of the techniques discussed in this book can also be applied to solving brain teasers.