Brainteasers Inappropriate for Job Interviews

Many types of brainteasers and puzzles simply do not belong in a job interview. For a variety of reasons, candidates will consider the following types of puzzles as either frivolous or, worse, a “gotcha” trap. In any case, they will alienate the candidate and bring disrepute on the organization. The difficulties with the following types of puzzles range from relying on a trick to being too frustrating, too culture-bound, too dependent on a particular language, or are too time consuming to solve.

Lateral Thinking Puzzles. Generally, these puzzles do not contain sufficient information for the solver to uncover the solution. These puzzles take the form of a seemingly strange or bizarre situation. The challenge is to interrogate the interviewer with questions that can be answered by one of only three possible answers—yes, no, or irrelevant. Lateral thinking puzzles. Good puzzles of this type call on an ability to challenge cultural assumptions and to reframe the situation in radical ways. When one line of inquiry reaches an end, then another approach is needed, often from a completely new direction. This is where the lateral thinking comes in.

While lateral thinking puzzles may give interviewers good information about how open-minded, flexible, and creative a candidate is, there is no avoiding the inherent gotcha factor of the exercise. But the major downside is that the lateral thinking puzzles are never quite solved; they are merely guessed at. That’s not to say that lateral thinking puzzles are not satisfying. The so-called elevator puzzle is one of the best known and most celebrated of all lateral thinking puzzles. Although there are many possible solutions that fit the initial conditions, only the canonical answer is truly satisfying.

A man lives on the tenth floor of a building. Every day he takes the elevator to go down to the ground floor to go to work or to go shopping. When he returns, if he is alone in the elevator he takes the elevator to the seventh floor and walks up the stairs to reach his apartment on the tenth floor. When he is with someone, he rides all the way to ten. When it’s raining outside, he also rides to ten, whether he is alone in the elevator or not. He hates climbing stairs so why does he do it?

Solution: The man is of such small stature that he cannot reach the button for floor 10. When he is not alone, his elevator mate pushes 10 for him. When it’s raining, the man has an umbrella he can use to extend his reach.

Logic Puzzles. Strictly speaking, logic puzzles require the construction of a grid to organize the clues. The clues take forms such as “Mr. Green lives between the model train enthusiast and the grocer, two doors from the blue house.” From an assortment of such clues one must deduce such things as the color and order of the houses on the street, the owners’ names, their occupations, and their hobbies. The puzzler isolates the solution by logical elimination of the possibilities. While these types of puzzles can speak to a candidate’s fact-gathering and organizing abilities, they are generally too tore and time-consuming to be appropriate for job interviews.

Liar-Truth Teller Puzzles. Generally liar-truth teller puzzles invoke two varieties of creatures, otherwise indistinguishable, except that one variety always tells the truth and the other variety always tells a lie. These puzzles generally set up a situation that requires the crafting of a carefully worded question that logically elicits the information desired to address the situation. These puzzles can be devilishly tricky, and success at solving them surely points to a highly verbal, logical intellect. On the other hand, having a conversation about such a puzzle can be very frustrating because of all the if statements required in its solution. For example:

In front of you are two doors. One door leads to the executive interview room and the other to an exit. Next to each door are identical-looking consultants, one from our company and one representing our rival. The consultant from our firm always tells the truth. The consultant from the rival firm always lies. You can’t tell which is which by looking. You are allowed to ask one consultant one question to find out which is the door to the executive interview room. What question do you ask?

Solution The key is to craft a question that gives you the information you want regardless of whether the consultant tells the truth or lies. Veteran puzzlers know that the way to do this is through the use of conditional statements creating double negatives. One strategy is to point at random to one door and ask, “If I asked you whether this is the way to the executive interview room, would you say it is?”

Math Puzzles. Math puzzles that require little more than computation or the ability to crunch numbers through a formula are simply not very interesting as brainteasers. Forget any puzzle that requires more than elementary arithmetic, geometry, or probability. Unless you’re interviewing for rocket scientists, calculus doesn’t belong in a job interview. Unless the job at hand requires specific mathematical skills, success at math proves little. If the job does require math, an aptitude test is a better way to go.

Trial and Error Puzzles. There are a variety of puzzles that are inventive and entertaining, but they require more or less brute force in their solution. Besides generally taking too much time to solve, such puzzles offer little in the way of discernment for either the interviewer or the interviewee. A classic example of such a problem is the following letter-substitution sum, said to be the entire contents of a postcard sent by a college student to his father. Each letter stands for a numeral. The goal is to determine what are the numbers of the sum (and the first task is to decide that it really is a sum):

Solution This monoalphabetic cipher has a unique solution. For those who want to figure this puzzle out with the help of an online puzzle worksheet, log onto Crack A Puzzle Online at http://www.geocities.com/Athens/Agora/2160/puzzle01.html. The site offers dozens of other such crypto-arithmetic puzzles. The unique solution for SEND + MORE = MONEY is 9,567 + 1,085 = 10,652.

Trick Questions. Gotcha questions can be fun, but they are not appropriate for job interviews. Interviewers need to understand that the power balance in job interviews is unequal. Besides not yielding useful information, trick questions can make candidates feel even more powerless. Thankfully, most interviewers left questions like this behind in sixth grade where they belong: “A plane crashes on the border between the United States and Canada. Where are the survivors buried? Solution: Survivors are never buried.” Trick questions can take on a veneer of respectability, but they are still trick questions:

Five men dig five holes five feet deep in five hours. How long will it take one man to dig a half a hole?

Solution: There is no such thing as half a hole.

Series Puzzles. These kinds of puzzles take the form of a series of apparently random letters or numbers, and the challenge is to identify the next number or letter in the series. There is, of course, an underlying rule or logic determining the series. Some series puzzles can be fun and even illuminating. Success at these puzzles points to a facile mind that can detect patterns, a skill that is no doubt useful in business. But series puzzles often revolve around a single theme or “aha” insight. Either candidates get the series or they don’t. Some may be culturally- or geographically-biased. Their biggest limitation as puzzles is that they don’t offer much opportunity to have a conversation with the candidate. Here’s an example

What is the next letter in this series: O, T, T, F, F, ____?

Solution: S for “six.” The series spells out numbers, one, two, three . . .

Here’s an example of a geographically-biased series puzzles:

What is the next number in the series 14, 23, 28, 33, 42, 51, ____?

Solution: 59 for 59th Street. The numbers represent the streets corresponding to the stops on New York City’s Lexington Avenue subway line.

Word Puzzles. Word puzzles administered in English are too dependent on language and culture and would discriminate against those whose first language is not English. Here’s an example of a word puzzle I would consider inappropriate for a job interview:

Can you name a word that uses the vowels A, E, I, O, U in order?

Solution: Facetious.