Brainteaser Interview Questions


A brainteaser is a form of puzzle that requires thinking in unconventional ways with given constraints in mind; sometimes it also involves lateral thinking. On a general scale, the most obvious answers are almost always the incorrect ones.


Sample Brainteaser Interview Questions

Call the switches 1, 2, and 3. Leave Switch 1 off. Turn Switch 2 on for five minutes and then turn it off. Turn Switch 3 on and leave it on. Enter the room. The bulb that is on is controlled by Switch 3 (the one you left on). Feel the light bulbs that are off for heat. The bulb that is off and warm is controlled by Switch 2 (the one you turned on, then off). The bulb that is off and cold is controlled by Switch 1 (the one that you didn't turn on).

Instead of describing what it looks like, try to identify what it does and how it can assist operations in the company by just going through and talking about its functionality, e.g., "this can be used to store contact details, make phone calls, send emails, take photos or videos, etc." You could also relate it to the job or the workplace and talk about how the mobile phone would be used.

If you charge 20 cents per vowel, the two-vowel word "apple" would cost 40 cents, three-vowel "banana" 60 cents, and four-vowel "grapefruit" 80 cents. Therefore a pear would cost 40 cents.

Try to answer this question with a lot of creativity and humor, like − “I would ask him if he remembers any movie where people used to look into a crystal ball and tell what was happening miles away. I would say Internet is that magic crystal ball of the present time.”

Don't think exponential growth and the kind of bacteria that's in the dish. If the bacteria doubles every minute, and it's full at 1 pm, it must have been half-full a minute earlier, at 12:59.

This question is designed in such a way that you can clearly identify a right and wrong option. However, this question will be correctly answered if you study the signals that the interviewer sends via gestures and body language. As a general rule, managers prefer “good and on time”, as they don’t appreciate work to stay pending because of the employees’ need for perfection.

These questions test what the candidate values and aspirations by asking them to think of a real person they know, and then describe what makes that person smart. Notable qualities are a person’s ability to think ahead several steps and execute those ideas, decision-making skills, and their ability to connect with others.

Let’s start drawing socks. There will be three scenarios −

  • If the first sock is red. If the second is red, you have a matching pair. But what if it is isn’t red?

  • If the second sock is yellow. If the third is either yellow or red, then you have a pair. If it is blue, then you draw again.

  • If the third sock is blue. Now you have one of each. Since your next sock must be either red, yellow, or blue, you are bound to have a pair.

Once you have four socks, you are guaranteed to have a pair.

Manhole covers are round so that they won’t fall into the manholes, as square covers could be dropped into the manholes if held diagonally.

Let’s say there are 50 coins and we separate 10 of them. Now we have a group of 10 and a group of 40.

Let’s assume there are 3 heads in the group of 10. Then there will be 7 heads in the group of 40.


Now we turn over all the coins in the group of 10.


That’s it! 7 heads in each group!