#4 memory size of any array

The question means the total bytes consumed by the element of the array. In order to clear up the misunderstanding, it is suggested to revise the question stem.

Z.nbytes is more direct then Z.size * Z.itemsize.

BTW, 4 typos: an hint -> a hint of of -> of every combinations -> every combination a two dimensional -> a two-dimensional

References: https://numpy.org/doc/stable/reference/generated/numpy.ndarray.nbytes.html https://docs.python.org/3/library/sys.html#sys.getsizeof