The trick is to just guess - with enough steps your errors will cancel each other out, unless you're grossly wrong, in which case you can go back and fix it.

The trick is to just guess - with enough steps your errors will cancel each other out, unless you're grossly wrong, in which case you can go back and fix it. Back when these were common interview questions, because Microsoft did it, bad interviewers would pick at whether you knew the "right" number for each step.