I do hate sums.  There is no greater mistake than to call arithmetic an
exact science.  There are permutations and aberrations discernible to minds
entirely noble like mine; subtle variations which ordinary accountants fail
to discover; hidden laws of number which it requires a mind like mine to
perceive.  For instance, if you add a sum from the bottom up, and then again
from the top down, the result is always different.
		-- Mrs. La Touche