If I were hiring a VP of engineering or CTO, my only goal in administering such a basic test would be to see whether they are offended and prepare to politely leave the interview. Not kidding here.
Sure, CTO duties can run a broad spectrum, depending on company size, etc. It could essentially mean "dev lead with a small team", all the way up to public company CTO with a good command of financials, managing budgets, large multi-level teams, etc. But, at either end and anywhere along that continuum, I would want to skip to probing higher-order thinking around architecture, strategy, people-management, etc.
So, if I've brought in people who I believe are adept at skills like these, I'd expect them to be confused and perhaps even insulted when I pull out a fizzbuzy integer summation problem.