The complex number obtained by taking the product of the integer two, the imaginary unit i, and the area π of a disc of radius 1 can be written — in principle — in six different ways:
$latex 2i\pi,\ 2\pi i,\ i2\pi,\ i\pi 2,\ \pi 2 i,\ \pi i 2.$
However, as far as I know, only the first two are commonly used. Or, to be more precise, I use exclusively the first form (which is much more euphonious when pronounced in French), and most everyone else uses the second form, with laughable justification.
