Write 63 in Binary
One of my coworkers likes to ask people to write 63 in binary when he interviews them.
Some of you might be thinking “that’s stupidly easy”, and many of you may be thinking “I have no idea and I hope I’m never asked that!”
There are many amusing answers to this request. Chief among them is to claim that they (in a computer or IT related field) have no need to know how to write a number in binary. That is the wrong answer. And shame on you for even considering such a thing — change professions immediately! If this question doesn’t appeal to you, then everything in Computer Science and Mathematics will seem like confusing magic and you’ll likely embarrass yourself on a daily basis. This is true for Project Managers, which is likely why so many PMs embarrass themselves all too often.
The correct answer, of course, is not to blurt out the binary string without even thinking, that would appear arrogant at best and cheating at worst. The correct answer is to either write or visibly start plotting out successive powers of 2, and upon reaching 64 (1000000) quickly slap your head at the realization that 63 is, in binary, 1 minus 1000000 therefor 0111111. You get partial credit for knowing, but demonstrating that you realized it was a silly question will get you full credit.
Now here is where the interview can get interesting. Why would a number like this be useful? What would happen if I bit-shift left or right? Suddenly a basic understanding of Boolean logic and Computer Science are uncovered! And at that point it becomes clear who is storing IP addresses as varchars and who is storing them as integers.