See my note. I don't ask the question in interviews. I think it is useless, they don't need it for their job. I do ask a variant of fizz buzz that requires using modulus. They don't get hired if they can't answer that one. So this subset of people I'm talking about are ones who do know modulus.
I ask it sometimes too - my favorite response opened with 'you want maintainability or speed' So I picked speed. They immediately set the first branch at mod 3 with the obvious justification - hired on the spot :-)