Remember those little logic puzzles your crazy uncle used to throw your way after Thanksgiving dinner to see if he could stump you? Well, they have been given new life and function in consulting, investment banking, and high-tech industry job interviews. Brainteaser cases can take many forms. Some are straightforward logic puzzles (for example, "If you have a drawer filled with eight white socks and 13 black socks, what is the smallest number you would have to pull out without looking in order to be sure that you had a matching pair?"). Other questions might not have a single correct answer. Instead, they may serve as a platform for you to demonstrate your creativity and ability to think "out-of-the-box." For example, your interviewer might ask you to list all the ways you could find a needle in a haystack.

It's always a good idea to let your interviewer know what you are thinking as you attack the question. Even if you don't end up with the right answer, your analytical ability will be on display. Also, if you do start down the wrong track, your interviewer may be kind enough to nudge you down another path.

Even if an idea seems really outlandish, you should probably offer it up. Brainteasers are often designed to showcase an individual's creativity. The only sure way not to get any points on such a question is to sit there like a rabbit in the headlights. Thump!

Sample Brainteaser (and Solution):

This is a little logic puzzle that could be given to undergrads, MBAs, or advanced-degree candidates.

You have eight balls, one of which is heavier than the others. All the balls appear identical. You have a balance-type scale, and you can perform trials on the balls. What is the minimum number of trials required to determine which is the heaviest ball?

Solution:

Two. You start by putting three balls on each side of the scale. There are two basic outcomes: one set of three is heavier, or both sets are in balance. If one set is heavier, you choose two balls from that set and weigh one on each side of the balance. If the balls balance, you know that the remaining one from the set is the heavy one. In the second outcome from the first measurement, the two sets of three balls are in balance. That means the heavy ball is among the remaining two. Weigh them, and you'll have your answer.

Source: The Net