Few programmers actually write correct code on a whiteboard... But your code doesn't have to be correct. Not as you first write it down, anyway. The advantage

Few programmers actually write correct code on a whiteboard... But your code doesn't have to be correct. Not as you first write it down, anyway. The advantage of writing the stupid and broken version of FizzBuzz first is that it gives you ample scope to demonstrate your ability to critique your own bad ideas out loud, write tests and conduct them out loud, eschew premature optimization, analyze the performance of something that's way too slow, and invent alternative approaches only after you've produced the stupidest thing that can possibly work. Not to mention your ability to stand in front of a whiteboard and talk while staying on task and not wasting time, which is a core skill in engineering, even if what you're doing on that whiteboard in real life is rarely actually writing code.