Google used to rely on brainteaser questions such as “How many golf balls would fit inside a 747 airplane?” and “If I shrank you to the size of a nickel and put you in a blender, how would you escape?”
But Google took a closer look at brainteasers’ predictive ability (comparing interview scores to later performance scores) and discovered that performance on these kinds of questions is at best a discrete skill that can be improved through practice, eliminating their utility for assessing candidates. At worst, brainteasers rely on some trivial bit of information or insight that is withheld from the candidate, and serve primarily to make the interviewer feel clever and self-satisfied. They have little if any ability to predict how candidates will perform in a job. This is in part because of the irrelevance of the task (how many times in your day job do you have to estimate the volume of an airplane?), and in part because there’s no correlation between general cognitive ability and insight problems like brainteasers.