On the answers of the question [Is $\frac{\textrm{d}y}{\textrm{d}x}$ not a ratio?](https://math.stackexchange.com/questions/21199/is-dy-dx-not-a-ratio) it was told that $\frac{dy}{dx}$ cannot be seen as a quotient, even though it looks like a fraction. My question is: does $dxdy$ in the double integral represent a multiplication of differentials? The problem than can be generalized for a multiple integral.