>>Hi everybody,
>>
>>This is a puzzle, which could be asked on a interview. I could not find a best answer.
>>
>>There is a 100 floor building. You have two glass balls. You need to find out the floor number, starting from which these balls will broke by minimal number of steps.
>>
>
>What is definition of a step in this case?

I think, one dropping of a ball is a step.