Brainteaser job interview questions are questions that test your thinking and show the interviewer how you solve problems. They may not have a right answer.
Brainteaser interview questions are mainly used in interviews for technical jobs, like computer coding. The interviewer wants to see how you come up with a solution, and how your mind works under pressure.
Brainteaser interview questions are uncommon outside these technical fields. They probably won’t come up unless the job needs you to be good at maths and solving difficult problems using logic.
Examples of brainteaser interview questions
Some brainteaser interview questions include:
- How would you weigh a bus without using scales?
- You have a three-litre jug and a five-litre jug. How do you measure one litre of water?
Do an online search for ‘brainteaser interview questions’ for more examples and solutions to brainteasers.
Tips for answering brainteaser interview questions
The trick to answering a brainteaser interview question is knowing that there’s usually not a single right answer.
The point is not so much about coming up with an answer (although you’ll be remembered if you find a creative solution). Instead, the interviewer wants to see how you:
- cope with pressure
- solve a problem using reasoning
- communicate your thought processes clearly.
Here are some tips for showing you can do those things. Let’s use weighing the bus as an example. See if you can come up with your own way to answer this brainteaser interview question.
1. Ask questions if you need to clarify anything
Ask the interviewer questions to clarify and define the problem. This also shows you’re engaging with the question right from the start.
For example, you could ask, ‘Do I have access to any other equipment?’
Keep asking questions until you’ve narrowed the problem down to a well-defined issue:
- ‘Does the bus need to be useable after I’ve weighed it?’
- ‘Can I take the bus apart?’
- ‘Does the bus have a manual or specifications sheet that shows its weight?’
2. Test your thinking
Once you’ve narrowed the problem down, state your thinking out loud, and explain why you thought this way:
- ‘Okay, so I’m assuming that the best way to approach this problem is to use Archimedes’ Principle.’
- ‘That’s because it’s probably the simplest way to weight an object without scales.’
The important thing is to explain your assumptions. In many brainteasers, you’ll have to come up with your own assumptions to solve the problem.
3. Explain your answers
This is what the interviewer really wants to hear. Don’t rush your answers to get to the solution you’ve found.
Talk them through it step by step, and explain why you’ve made each decision you have.
- ‘I’m going to solve this problem using the principle that an object that floats displaces an equal weight of water.’
- ‘I’m going to find a barge that I can drive the bus onto. When the bus is on the barge, I’m going to mark where the waterline is.’
- ‘That will give me a measure of the water that’s been displaced by the weight of the bus.’
- ‘Then I’m going to drive the bus off the barge,and fill the barge with objects that I know the weight of.’
- ‘When the mark I made is at the waterline, I’ll know how much the bus weighs.’
If the brainteaser involves calculations, use a whiteboard or a piece of paper to write down your calculations. This will show the interviewer the steps you took to calculate your answer.
Solution to the jug brainteaser example
For the second example question you could answer it in the following way:
- I would take the three-litre jug and fill it to the top with water.
- I would then pour the three litres of water into the five-litre jug.
- I would then fill the three litre jug again, and use it to fill the five-litre jug all the way to the top. That would leave me with one litre left in the three-litre jug.