How to survive brain teaser interview questions

Is it not enough to have a résumé bursting with accomplishments, an action plan for how you can benefit the company and a winning interview style to land the job? Now, you're also expected to answer brain-teaser questions? Seriously? Seriously. "This trend toward asking off-the-wall questions started in high tech a few years ago and has now emerged in interviews for jobs in a variety of fields," says John O'Connor, president of North Carolina-based CareerPro Inc., a professional career-coaching and branding company.
These questions are often brain teasers and can be anything from a complex, multilayered math and logic problem to a wacky question with no real answer.
Some examples include:

1.How many rocks are on the face of the moon?
2.How many jellybeans can fit into a gallon jar?
3.Why are manhole covers round instead of square?
4.How many pounds of breakfast cereal are sold in the U.S. every year?
5.What are the decimal equivalents of 5/16 and 7/16?.

It may seem like some sort of interviewee hazing, but there's often a method to the madness. In many cases, you won't be expected to come up with the right answer. In fact, the interviewer might not even know the answer. "They're more interested in your thought process and your ability to present ideas, debate and think creatively," O'Connor says. "They want to see candidates who can walk them through their way of thinking. And they're looking for candidates who will be thrown a curveball and not freak out."

i)Bring tools.
Show up to the interview with pens, paper, markers, calculator, stopwatch and ruler to work out a possible brain teaser. It's unlikely that you'll be asked, point blank, how many times heavier an elephant is than a mouse and be expected to answer it on the spot. You'll have time. And depending on the job and the field, what you do on your scratch paper is more important than the conclusion you reach.
ii)Don't be shocked or offended.
A question might surprise you or seem silly given the job for which you're interviewing. Don't let it throw you. Again, the answer is usually not the destination. Sometimes the wackiest question deserves an equally wacky process to reach a conclusion. But do take the questions seriously. Don't assume that it's being asked to tick you off or make you the butt of a human-resources joke.
iii)Question the question.
Show your ability to think through a problem by asking a clarifying question regarding the brain teaser, suggests Paul Bailo, a New York-based recruiter and author of "The Official Phone Interview Handbook." "Asking a follow-up question will give your mind a break and buy you time to help you fully understand what is being asked so you don't solve the wrong problem," Bailo says.
iv)Speak out your logic.
Listen to what you are thinking, Bailo adds. "Sounding out" the process of reaching an answer can help you think through the process in a different way. "Leveraging the logical speaking method will allow for a quicker answer and faster mental processing," he says. "Think of it as reading a book out loud, only the book you are reading out loud is your mind thinking through a problem."
v)See what you are thinking.
Just like sounding out a problem can give your brain a productive whack, drawing it out can help you edit and improve your approach.
vi) Practice.
You can't prepare for the exact question unless you're sure you know what they'll ask. But you can exercise your mind by reading philosophy books, playing mental games, doing crossword puzzles and thinking about big problems, O'Connor says. "How would you solve the world energy crisis? What would the world do without drinking water? Think of these exercises as a workout for your mind."