Besides, if you had said "then I search the number online" then it's plausible the interviewer would ask what would you do if you didn't find anything relevant right away. For instance, if you search for my cell phone number, you get 0 results connected with me.
The flip side is when the interviewer doesn't communicate well. Or asks a specific question, but means something slightly different.
I've dealt with that before. Assumed they meant what they said, when the reality was, they were being more precise than intended. My fault for assuming I guess. I now try to clarify the intent, and make clear the precision.
I understand fermi tests are intended to show broad problem solving abilities, but imho, these tests are for lazy people. Talk to a candidate for 20 minutes. If you can't tell if he/she is suited for the role, or at least for a follow up interview, one of you is not qualified.
That said, I don't think they're lazy questions necessarily. However, I'm a physicist, enjoy Fermi problems (actually compulsively do the calculations when I hear a new one - a million golf balls!), and do think that order of magnitude approximations and quick unit changes are important skills to have developed.
I do think it's very lazy when they come out of a book or are riddles, because there are so many short approximations we can do at any moment. How much will the electric bill be for this office when it's August? or I just made a pot of coffee and forgot to place it back on the burner - when will it be too cold to enjoy? No accurate answer is needed or cared about, but the ability to predict important factors and come up with a list of contributing components is important.
He's like 'notice the small bevel at the bottom of the center key". Apparently he didn't know what it was called and that it was named after the inventor. Well, technically it's not proper Braille, but i would have taken that as a correct answer.
I just wanted to highlight that even though the candidate/me was aware of the basic concept. The answer just wasn't the exact thing the interviewer was looking for, hence it was wrong according to him.
It boils down to me not being perfectly clear, I guess. No hard feelings or anything, of course. Like I said, I threw myself off my game anyway.
I asked if it had the phone number, they said yes, and I said the numbers are the same as in English... They said "okay, what next?" ... I was stuck. Next? Well, I suppose I could take a photo of it and ask for someone to translate it online... Or find someone in real life to translate it for me...
After a couple of minutes, they were ready to move on, disappointed, when I said "Well, short of asking for help, or Googling the phone number, I have no idea off hand how to find it."
"Oh, well, searching the number, that's what we thought you were going for initially."
It was. I'd thought they meant "next" as in "other than that method". Having the number was so evidently "problem solved" for me, that I didn't explicitly say "search out online". ... I suddenly felt like I was in grade school again, and my teacher had failed me for not showing the work in math class. I had the right answer, but would never get credit. I went on to flop the next question or two, as I vaguely recall.