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I'm stuck with the following question which is taken from SAT-like exam:

How many $ 5 \times 5 $ ceramic tiles are needed to cover rectangular area whose size is $ 10^4 $ units squared (you can't cut the tiles).

The answer that I've got is $400$ (${10^4} \over {5*5}$), however, it is wrong. I don't understand where's the problem. I would appreciate any help.

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    The question is not well-worded. Your answer of $400$ is reasonable under certain natural assumptions. But if the rectangle has one side equal to $1$ unit, or $10\sqrt{2}$ units, then $400$ won't do the job. If the last suggested answer had been "It depends," that choice would have been right.2012-12-12
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    @AndréNicolas I pasted here the question "as it is". I'm quite sure that the question suggests that the sides are divisible by 5, because you can't cut the tiles and they must completely fill the whole rectangular form. Let's think logically - if the sides hadn't been divisible by 5, then you would have to cut the tiles (as they are 5×5). But we aren't allowed to cut them, so the sides must be divisible by 5. However, then the only answer is 400. So I'm certain that this is a mistake or just a very bad-worded question.2012-12-12
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    By "cover" one can mean that possibly some of the tiles stick out beyond the rectangle. That in fact is the technical meaning of cover. (But that technical meaning cannot be expected to be known to people taking a SAT-level test.) By the way, I am replying "blind" since the link, if there was one, doesn't work.2012-12-12
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    @AndréNicolas Well, it could be. However there is no such answer as "depends on shape", so it could be that the question is poorly-worded or there is some mistake in the book. Anyway, thank you for your suggestions.2012-12-12

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