America's toughest job interview questions

Even though employers are creating new jobs, many are adding tougher interview questions or asking applicants to perform skill tests as a way to skim the cream of the crop. 

That trend means applicants need to be prepared for anything, including strange and difficult questions from hiring managers, according to research from employment site Brain teasers were a hallmark of Google’s (GOOG) hiring process, and although the company has since backed away from the technique, plenty of other companies have taken up the mantle. 

Some evidence shows that tough interview questions pay off: Previous research from Glassdoor found such logic-stumpers can result in happier hires. Employees who reported going through a relatively tough interview process were more pleased with their jobs. Glassdoor economist Andrew Chamberlain compared it to dating. Taking time to find the right match between employer and candidate pays off in the long run by leading to higher satisfaction and productivity. 

Preparing for a job interview should include researching the company via online sources as well as talking with current and former employees about what to expect. Tapping insiders can help unearth insights into what types of jobs or skills a company is searching for.  

On top of that, Glassdoor recommends practicing answers to questions out loud with a friend or talking in front of a mirror. Second, prepare a list of questions you’d like to ask, so that you’re prepared for the standard interview question: “So, have any questions for us?”

Here are 27 of the toughest job interview questions reported by Glassdoor users during the past year. 

1. “How do you explain a vending machine to someone who hasn’t seen or used one before?” - Global data analyst at Bloomberg 

2. “How many fire hydrants are there in Los Angeles County?” - Software engineer at Disney Interactive Studios

3. “If your current employer had an anniversary party for you, what five words would be written on the cake to describe you?” - District manager at Express

4. “Who in history would you want to go to dinner with and why?” - Flight attendant, at PSA Airlines

5. “Prove that hoop stress is twice the longitudinal stress in a cylindrical pressure vessel.” - Test operations engineer at SpaceX

6. “What’s the capital of Canada?” - Team leader at OpticsPlanet

7. “Name a brand that represents you as a person.” - Brand strategist at Twitter

8. “Estimate how many employees are in the next building” - Data scientist at Risk Management Solutions

9. “How many happy birthday posts do you think Facebook gets in one day?” - Sales operations at Facebook

10. “If you could take anyone on a road trip with you, who would you take and why?” - Educator at lululemon

11. “What’s the first thing you’d print with a 3D printer if you had one?” - Linux systems administrator at Rackspace

12. “If you had to take only one item to a deserted island, what would that be?” - Customer service specialist at Squarespace

13. “Please describe an instance where you had to make a decision without all of the necessary information.” - Analytics at athenahealth

14. “How do you reverse a text string on the Unix command line?” - Developer at Capital One

15. “If you’re in a boat with a boulder and you drop that boulder into the lake, how does the water level before and after you drop the boulder in the lake compare?” - Mechanical design engineer at Apple

16. “You have been asked to lead a multimillion dollar, multiyear grant that will be supported across several companies and universities. How do you start?” - Research scientist at Ford Motor Company

17. “Sell me on one idea, and then sell me on the opposite of that idea.” - Solarwinds administrator at Blizzard Entertainment

18. “How would you go about finding the top five Java developers in a certain area.” - Technical recruiter at Google

19. “What’s the probability of an integer from 1 to 60,000 not having the digit 6?” - Quantitative developer at AKUNA CAPITAL

20. “If you were a Muppet, which character would you be?” - Donor family advocate at LifeNet Health

21. “Give me 48 cents using six coins. Tell me quantity and value of the six coins.” - Human resource manager at Wintec

22. “Write an equation to optimize the marketing spend between Facebook and Twitter campaigns.” - Analyst (data science) at Uber

23. “What is the angle at 3:15?” - Implementation consultant at Fast Enterprises

24. “What part of the newspaper do you read first? What does this say about you?” - Audit at BDO USA

25. “If a co-worker had an annoying habit, and it hindered your quality of work, how would you resolve it?” - Production technician at Procter & Gamble

26. “Throw your resume aside and tell me what makes you you.” - Sales executive at Zillow

27. “How would you find the square root of 1.2?” - Hardware engineer at Jump Trading