The purpose of that kind of question is not to get a piece of information, it's to evaluate how you go about solving problems that you don't know the answer to and/or don't have immediately obvious ways (like using a calculator) to find the solution.
Your comment has me wondering what it is specifically I find so irksome about the interview question in the blog post. In one of my first interviews they gave me a fairly well know riddle and asked me to work out the answer on a white board in front of them. I had no problem with that, actually I found it pretty fun. There’s something about this question, I haven’t figured it out quite yet, that bothers me more than other analysis questions. Maybe it’s just the flavor the writer added to it, I’ll have to figure that out.
Yeah, you type it into a calculator. In what universe would I need to know this answer and NOT type it into a calculator? It isn't because I can't work it out, it's because I am a dumb human who makes mistakes and if I am trying to work out that exact number, it is because it matters. And if it matters, I don't want to fuck it up.
Well I’m not that interviewer, but I’m pretty sure that getting the exact answer is not really the point of the exercise. Understanding how the candidate thinks, does mental calculations, etc. is the point, and anyone that is hostile to this basic exercise is probably too unpleasant to be a desirable coworker anyway.
I don't know if you read that reply as hostile or just saying "hostile in general" but I can promise there was a smile on my face and it wasn't "hostile" at all. The mental calculations is a pointless exercise. Math is so incredibly different than big-system software, and it is more about working memory than anything else, and solving arbitrary math problems won't get you that feedback.
I didn’t mean literally hostile. More like, “if this candidate would rather get into an argument or simply not complete the challenge we’ve presented them with, then they’re not going to be a good employee.”
Companies want to hire people that do things, not question everything, regardless of whether those things ought to be questioned. You’re being hired to achieve business objectives, full stop.