Brainteasers. You might remember them from university interviews. They’re the questions you can’t really prepare for, the ones that may or may not have a right answer and always require you to think on your feet.
One physics professor often asks A-Level students, “What happens when you light a candle on in zero gravity?” He doesn’t expect them to get the answer right. The point is to see how they approach the question.
(In case you’re interested, the flame forms a slow-burning globe around the wick.)
Brainteasers are just as common in job interviews, particularly for internships and graduate schemes where the candidates don’t have a lot of real work experience to explore. Here’s a quick rundown of five key types you might encounter.
The ones that make you go, “Huh?”
The old-school brainteaser
Remember this golden oldie?
“You have a wolf, a goat and a cabbage, and you’re trying to cross a river. There’s a rowing boat big enough for you and one other thing. You can take as many trips as you like – but you can’t leave the wolf alone with the goat, or the goat alone with the cabbage. How do you get everything across safely?”
That’s an easy one, but you may come across one in an interview that’s really fiendish. Fortunately, they’re going out of fashion. They aren’t really helpful to interviewers – you’ll either get the answer or you won’t, and it’s probably about 50% luck. Really, the point is to make you sweat and see how you handle it – so remember to bring a notepad and just stay calm.
Want a practice run? Take Bright Network's practice test.
The estimation question
How many six-year-olds are there in Utah? How many grains of sugar would fit in a teaspoon?
These questions need a combination of basic maths, educated guesswork and common sense. The point is to get to a vaguely plausible estimate by an appropriate method. For the six-year-olds question, for example, you need to find sensible ways to estimate the population of Utah and the percentage of six-year-olds in the general population.
The real point is that you mustn’t say, “I don’t know.” (They know that already.) Another bad response is, “Can you tell me the population of the US overall?” (They won’t.)
Grab a pencil and have a go. It’s important to think aloud so your interviewer understands your approach.
The real world question
Like the candle in zero gravity example, these ask you to think logically through a topic you probably haven’t considered before. Why is a tennis ball fuzzy? Where do albatrosses sleep?
It’s all about the approach. Again, you need to think aloud. List as many viable possibilities as you can come up with, and then compare them to see which is the most likely.
The communication question
How would you explain supply and demand to a six-year old? A non-English speaker needs to come and use your washing machine while you’re out – what instructions do you leave?
While most brainteaser questions are, arguably, about making you squirm and giving your interviewer some free entertainment, this is perhaps the most useful type. It tests specific skills that almost everyone needs – communication and relating to others. Your job is to judge the other person’s needs and tailor your explanation accordingly. You can definitely take a few moments of quiet before you tackle this one. You need to think carefully about your audience and how best to get your points across.
The oddball question
Yes, some of them are just plain weird.
- If you were an ice cream flavour, what would you be?
- Would you rather fight a hundred duck-sized horses or one horse-sized duck?
- How would you paint London purple?
- Tell me a joke.
These are the kind of questions that come to mind on the way home from the pub, when you chat with your mates, just for fun. And sometimes, that’s the point. As well as testing whether you can roll with the punches, these test whether you’re the kind of person who’ll fit into the company culture. Are you relaxed or intense, thoughtful or funny? Will you get on with the other people in the office, if you end up having one of these silly discussions over lunch?
There’s no way to win this except to be yourself. Just go with the flow.
And finally…
Don’t panic. A lot of interviewers find brainteaser questions unhelpful. You may not encounter one. If you do, it probably won’t count for all that much compared to the questions about your skills and talents. So long as you know what’s expected of you and don’t freeze up, you’ll be fine.
Some interviews may contain a brainteaser question, so it's important to be prepared just in case. Learn how to ace an interview with Bright Network Academy and Willis Towers Watson's graduates and recruitment team.