I still think how many golf balls fit in a 747 is a good interview question. No one needs to give me a number but someone could really wow me but outlining a real plan to estimate this, tell me how you would subcontract estimating the size of the golf ball and the plane. It's not about a right or wrong answer but explaining to me how you think. I do software and hardware interviews and always did them in person so we can focus on how a candidate thinks. You can answer every question wrong in my interview but still be above the bar because of how they show me they can think.