Brain Teaser Interview Questions and Answers


Brain Teaser Interview Questions and Answers

answers brain teaser interview questions that are commonly asked at job interviews for technical and quantitative roles. These questions focus on problem solving, spatial reasoning, and understanding.

By reading this document, you’ll be better prepared to answer unexpected questions, think outside the box, and elaborate on non-standard solutions. And most importantly, you’ll be calm and relaxed at the interview.

Answers to  brain teaser interview questions including:

    • How do you find your car along a very long street when you don’t remember where you parked it?
    • We want to merge 4 companies into one large company. How many ways are there to merge them?
    • I have a rectangular piece of cheese with a round hole. How do I cut the piece with one straight lien into two parts of equal weight?
    • There are a number of stones, all of different weights. The 10 lightest stones weigh 40% of the total weight. The 5 heaviest stones weigh 25% of the total weight. How many stones are there?
    • What is the avg. of the smaller of three random numbers of 0 to 1?
    • “1” costs $10. “20” costs $20. How much does “100” cost?
    • It takes 6 people 48 hours to paint a house. How long would it take to paint the house if 3 people were added to the middle of the project?
    • 3 apples were weighed in pairs and the weights were 200, 204, 208 grams. What is the weight of the lightest apple?
    • You are shrunk so that your height is equal to the diameter of a dime (a ten-cent coin) and your mass is proportional reduced so as to maintain your original density. Who is heavier, you or the dime?
    • I roll two dice. What is the probability that the 2nd number is greater than the 1st?


ImageI confess that I was not on top during an interview for a job at Google. The interviewer was the manager who gave his name to one of the social networks. He was very nice guy. He asked me a question:

“What is your strategy to find your car along a very long street if you don’t remember the parking place?”

Being under interview pressure, I quickly improvised an answer like this: I double the distance every time I change direction.

The mathematically correct answer might be the linear search.

To go X blocks (cars) in one direction, then 2X in the other, then 4X forwards, 8X in the reverse direction etc… The initial X depends on the standard deviation.

Now I have time to think about the real problem, I find that the theoretically correct answer is not correct for real life. My mistake was sticking to the initial data; I did not think about the real situation. There are no infinite streets in real life.

One of the practical approaches is : choose a direction and go until the end;  if I am not lucky, then go in the other direction.

When I ask a manager about the solution he said: “I will use the key signalization to find my car.” This is “a management solution”.

Is this problem an example of the math paradox: the theoretical solution is not the same as the practical choice? There are many anecdotes about mathematicians: mathematicians are absolutely right and absolutely useless.

Here the list of 140 questions at Google:

Recently, the senior vice president of people operations at Google admits that certain brainteasers are useless.

When I applied to my recent job, there were not formal interviews. We just discussed business development. At a dinner, the company owner asked funny coin puzzles. I was the first who correctly answered. I got the job.

I still think that such challenges are very useful. I do it.  Engineering and non-HR managers still informally use such questions.

I did not get the job at Google and I am happy about that. Since that time, I have collected logic problems and put 150+ questions/answers into a book titled Job Interview Logic Puzzles. This is a great help for engineers and managers who want to be ready for challenging interview questions.